diff --git a/src/uucore/Cargo.toml b/src/uucore/Cargo.toml
index 03b6df7fb1d..3713f429ea4 100644
--- a/src/uucore/Cargo.toml
+++ b/src/uucore/Cargo.toml
@@ -22,7 +22,6 @@ path = "src/lib/lib.rs"
 ariadne = { workspace = true, optional = true }
 base64-simd = { workspace = true, optional = true }
 bstr = { workspace = true, optional = true }
-clap = { workspace = true }
 data-encoding = { workspace = true, optional = true }
 data-encoding-macro = { workspace = true, optional = true }
 dunce = { workspace = true, optional = true }
@@ -37,7 +36,6 @@ libc = { workspace = true, optional = true }
 openssl = { workspace = true, optional = true }
 os_display = { workspace = true }
 rustc-hash = { workspace = true }
-rustix = { workspace = true, features = ["fs", "net", "pipe", "process"] }
 # Not optional: os_display already pulls unicode-width into every uucore build,
 # so making it a direct dependency here is free and keeps char_width available
 # on all targets (a feature-gated optional dep failed to activate on wasm).
@@ -91,18 +89,29 @@ thiserror = { workspace = true }
 [dev-dependencies]
 tempfile = { workspace = true }
 
+[target.'cfg(not(target_os = "horizon"))'.dependencies]
+# TODO: https://github.com/eminence/terminal-size/pull/78
+clap = { workspace = true }
+rustix = { workspace = true, features = ["fs", "net", "pipe", "process"] }
+
 [target.'cfg(any(target_os = "linux", target_os = "android"))'.dependencies]
 selinux = { workspace = true, optional = true }
 
+[target.'cfg(any(target_vendor = "apple", target_os = "cygwin", target_os = "freebsd", target_os = "linux", target_os = "netbsd"))'.dependencies]
+dns-lookup = { workspace = true, optional = true }
+
 [target.'cfg(unix)'.dependencies]
 # utmpx is unix-only, so its dependencies must not be pulled into other targets
 # (the uptime feature enables utmpx and now builds on windows too).
-dns-lookup = { workspace = true, optional = true }
 time = { workspace = true, optional = true, features = [
   "formatting",
   "local-offset",
   "macros",
 ] }
+walkdir = { workspace = true, optional = true }
+xattr = { workspace = true, optional = true }
+
+[target.'cfg(all(unix, not(target_os = "horizon")))'.dependencies]
 nix = { workspace = true, features = [
   "dir",
   "fs",
@@ -112,8 +121,6 @@ nix = { workspace = true, features = [
   "user",
   "zerocopy",
 ] }
-walkdir = { workspace = true, optional = true }
-xattr = { workspace = true, optional = true }
 
 [target.'cfg(target_os = "linux")'.dependencies]
 procfs = { workspace = true, optional = true }
diff --git a/src/uucore/src/lib/features.rs b/src/uucore/src/lib/features.rs
index c35b076c956..286929767fd 100644
--- a/src/uucore/src/lib/features.rs
+++ b/src/uucore/src/lib/features.rs
@@ -125,12 +125,14 @@ pub mod smack;
 #[cfg(feature = "feat_systemd_logind")]
 pub mod systemd_logind;
 #[cfg(all(
-    unix,
-    not(target_os = "android"),
-    not(target_os = "fuchsia"),
-    not(target_os = "openbsd"),
-    not(target_os = "redox"),
-    feature = "utmpx"
+    feature = "utmpx",
+    any(
+        target_vendor = "apple",
+        target_os = "cygwin",
+        target_os = "freebsd",
+        all(target_os = "linux", not(target_env = "ohos")),
+        target_os = "netbsd"
+    )
 ))]
 pub mod utmpx;
 // ** windows-only
diff --git a/src/uucore/src/lib/features/process/unix.rs b/src/uucore/src/lib/features/process/unix.rs
index 6b98758f4f0..9b3b6a48ca8 100644
--- a/src/uucore/src/lib/features/process/unix.rs
+++ b/src/uucore/src/lib/features/process/unix.rs
@@ -12,20 +12,20 @@
 use libc::{gid_t, pid_t, uid_t};
 #[cfg(not(target_os = "redox"))]
 use nix::errno::Errno;
-#[cfg(not(target_os = "fuchsia"))]
+#[cfg(not(any(target_os = "fuchsia", target_os = "haiku")))]
 use nix::sys::signal::{self as nix_signal, SigHandler};
 use nix::sys::signal::{SigSet, Signal};
 use nix::unistd::Pid;
 use rustix::process::Signal as RixSignal;
 use std::io;
-#[cfg(not(target_os = "fuchsia"))]
+#[cfg(not(any(target_os = "fuchsia", target_os = "haiku")))]
 use std::process::Child;
-#[cfg(not(target_os = "fuchsia"))]
+#[cfg(not(any(target_os = "fuchsia", target_os = "haiku")))]
 use std::time::{Duration, Instant};
-#[cfg(not(target_os = "fuchsia"))]
+#[cfg(not(any(target_os = "fuchsia", target_os = "haiku")))]
 use timer::Timer;
 
-#[cfg(not(target_os = "fuchsia"))]
+#[cfg(not(any(target_os = "fuchsia", target_os = "haiku")))]
 use super::{ChildExt, TimeoutRet};
 
 /// `geteuid()` returns the effective user ID of the calling process.
@@ -83,7 +83,7 @@ pub fn getsid(pid: i32) -> Result<pid_t, Errno> {
     nix::unistd::getsid(pid).map(Pid::as_raw)
 }
 
-#[cfg(not(target_os = "fuchsia"))]
+#[cfg(not(any(target_os = "fuchsia", target_os = "haiku")))]
 impl ChildExt for Child {
     fn send_signal(&mut self, signal: usize) -> io::Result<()> {
         let pid = Pid::from_raw(self.id() as pid_t);
@@ -180,7 +180,7 @@ pub fn unblock_signal(signal: RixSignal) -> io::Result<()> {
 /// Ensures there is no overflow on time_t operations. Some BSDs (notably XNU)
 /// will return EINVAL otherwise; POSIX only defines it up to 10e8, so we cap
 /// it on all targets we do not trust to support the full integer range.
-#[cfg(not(target_os = "fuchsia"))]
+#[cfg(not(any(target_os = "fuchsia", target_os = "haiku")))]
 const MAX_KTIME_T: Duration = if cfg!(target_os = "linux") {
     Duration::from_secs(9_223_372_036)
 } else {
@@ -193,6 +193,7 @@ const MAX_KTIME_T: Duration = if cfg!(target_os = "linux") {
 #[cfg(not(any(
     target_vendor = "apple",
     target_os = "fuchsia",
+    target_os = "haiku",
     target_os = "openbsd",
     windows
 )))]
@@ -348,7 +349,7 @@ mod timer {
     }
 }
 
-#[cfg(not(target_os = "fuchsia"))]
+#[cfg(not(any(target_os = "fuchsia", target_os = "haiku")))]
 impl Timer {
     fn timed_sigwait(&mut self, timeout: Duration) -> io::Result<Option<Signal>> {
         self.arm(timeout)?;
diff --git a/src/uucore/src/lib/lib.rs b/src/uucore/src/lib/lib.rs
index df560c376bb..734ddb9a211 100644
--- a/src/uucore/src/lib/lib.rs
+++ b/src/uucore/src/lib/lib.rs
@@ -7,6 +7,8 @@
 //
 // spell-checker:ignore sigaction SIGBUS SIGSEGV extendedbigdecimal myutil logind
 
+#![cfg(not(any(target_os = "aix", target_os = "horizon")))]
+
 // * feature-gated external crates (re-shared as public internal modules)
 #[cfg(feature = "libc")]
 pub extern crate libc;
@@ -102,7 +104,7 @@ pub use crate::features::perms;
     any(feature = "pipes", feature = "buf-copy")
 ))]
 pub use crate::features::pipes;
-#[cfg(all(any(unix, windows), feature = "process"))]
+#[cfg(all(any(all(unix, not(target_os = "aix")), windows), feature = "process"))]
 pub use crate::features::process;
 #[cfg(all(unix, feature = "safe-copy"))]
 pub use crate::features::safe_copy;
@@ -130,12 +132,14 @@ pub use crate::features::safe_traversal;
 ))]
 pub use crate::features::signals;
 #[cfg(all(
-    unix,
-    not(target_os = "android"),
-    not(target_os = "fuchsia"),
-    not(target_os = "openbsd"),
-    not(target_os = "redox"),
-    feature = "utmpx"
+    feature = "utmpx",
+    any(
+        target_vendor = "apple",
+        target_os = "cygwin",
+        target_os = "freebsd",
+        all(target_os = "linux", not(target_env = "ohos")),
+        target_os = "netbsd"
+    )
 ))]
 pub use crate::features::utmpx;
 // ** windows-only
diff --git a/tests/uutests/Cargo.toml b/tests/uutests/Cargo.toml
index e9cae7704aa..3bd13446cea 100644
--- a/tests/uutests/Cargo.toml
+++ b/tests/uutests/Cargo.toml
@@ -24,7 +24,6 @@ libc = { workspace = true }
 pretty_assertions = { workspace = true }
 rand = { workspace = true }
 regex = { workspace = true }
-tempfile = { workspace = true }
 uucore = { workspace = true, features = [
   "mode",
   "entries",
@@ -33,12 +32,15 @@ uucore = { workspace = true, features = [
   "utmpx",
 ] }
 
-[target.'cfg(any(target_os = "linux", target_os = "android"))'.dependencies]
+[target.'cfg(not(target_os = "horizon"))'.dependencies]
+tempfile = { workspace = true }
 
-[target.'cfg(unix)'.dependencies]
-nix = { workspace = true, features = ["process", "signal", "term", "user"] }
+[target.'cfg(all(unix, not(target_os = "fuchsia")))'.dependencies]
 rlimit = { workspace = true }
 
+[target.'cfg(all(unix, not(any(target_os = "aix", target_os = "horizon"))))'.dependencies]
+nix = { workspace = true, features = ["process", "signal", "term", "user"] }
+
 [target.'cfg(all(unix, not(any(target_vendor = "apple", target_os = "openbsd"))))'.dependencies]
 xattr = { workspace = true }
 
diff --git a/tests/uutests/src/lib/lib.rs b/tests/uutests/src/lib/lib.rs
index 05e2b13824c..ae0f82c972a 100644
--- a/tests/uutests/src/lib/lib.rs
+++ b/tests/uutests/src/lib/lib.rs
@@ -2,7 +2,9 @@
 //
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
+
 #[macro_use]
 pub mod macros;
 pub mod random;
+#[cfg(not(any(target_os = "aix", target_os = "horizon")))]
 pub mod util;
diff --git a/tests/uutests/src/lib/util.rs b/tests/uutests/src/lib/util.rs
index 5559a654aad..5624da1efdd 100644
--- a/tests/uutests/src/lib/util.rs
+++ b/tests/uutests/src/lib/util.rs
@@ -16,14 +16,14 @@
 use core::str;
 #[cfg(unix)]
 use libc::mode_t;
-#[cfg(unix)]
+#[cfg(all(unix, not(any(target_os = "fuchsia", target_os = "redox"))))]
 use nix::pty::OpenptyResult;
 #[cfg(unix)]
 use nix::sys;
-#[cfg(not(windows))]
+#[cfg(unix)]
 use nix::sys::stat::{self, SFlag};
 use pretty_assertions::assert_eq;
-#[cfg(unix)]
+#[cfg(all(unix, not(target_os = "fuchsia")))]
 use rlimit::setrlimit;
 use std::borrow::Cow;
 use std::collections::VecDeque;
@@ -340,8 +340,11 @@ impl CmdResult {
     ///
     /// # Platform specific behavior
     ///
-    /// This assertion method is only available on unix systems, except for fuchsia.
-    #[cfg(all(unix, not(target_os = "fuchsia")))]
+    /// This assertion method is only available on unix systems
+    #[cfg(all(
+        unix,
+        not(any(target_os = "fuchsia", target_os = "haiku", target_os = "hurd"))
+    ))]
     #[track_caller]
     pub fn signal_name_is(&self, name: &str) -> &Self {
         use uucore::signals::signal_by_name_or_value;
@@ -1197,7 +1200,7 @@ impl AtPath {
         File::create(self.plus(file)).unwrap();
     }
 
-    #[cfg(not(windows))]
+    #[cfg(unix)]
     pub fn mkfifo(&self, fifo: &str) {
         // rustix::fs::mkfifoat is linux only
         use nix::sys::stat::Mode;
@@ -1215,13 +1218,13 @@ impl AtPath {
         UnixListener::bind(full_path).expect("Socket file creation failed.");
     }
 
-    #[cfg(not(windows))]
+    #[cfg(unix)]
     pub fn is_fifo(&self, fifo: &str) -> bool {
         stat::stat(&self.plus(fifo))
             .is_ok_and(|s| SFlag::from_bits_truncate(s.st_mode).contains(SFlag::S_IFIFO))
     }
 
-    #[cfg(not(windows))]
+    #[cfg(unix)]
     pub fn is_char_device(&self, char_dev: &str) -> bool {
         stat::stat(&self.plus(char_dev))
             .is_ok_and(|s| SFlag::from_bits_truncate(s.st_mode).contains(SFlag::S_IFCHR))
@@ -1239,6 +1242,7 @@ impl AtPath {
         hard_link(self.plus(original), self.plus(link)).unwrap();
     }
 
+    #[cfg(any(unix, windows))]
     pub fn symlink_file(&self, original: &str, link: &str) {
         log_info(
             "symlink",
@@ -1251,6 +1255,7 @@ impl AtPath {
         symlink_file(self.plus(original), self.plus(link)).unwrap();
     }
 
+    #[cfg(any(unix, windows))]
     pub fn relative_symlink_file(&self, original: &str, link: &str) {
         #[cfg(windows)]
         let original = original.replace('/', MAIN_SEPARATOR_STR);
@@ -1261,6 +1266,7 @@ impl AtPath {
         symlink_file(original, self.plus(link)).unwrap();
     }
 
+    #[cfg(any(unix, windows))]
     pub fn symlink_dir(&self, original: &str, link: &str) {
         log_info(
             "symlink",
@@ -1273,6 +1279,7 @@ impl AtPath {
         symlink_dir(self.plus(original), self.plus(link)).unwrap();
     }
 
+    #[cfg(any(unix, windows))]
     pub fn relative_symlink_dir(&self, original: &str, link: &str) {
         #[cfg(windows)]
         let original = original.replace('/', MAIN_SEPARATOR_STR);
@@ -1376,7 +1383,7 @@ impl AtPath {
     ///
     /// This function panics if there is an error loading the metadata
     /// or setting the permissions of the file.
-    #[cfg(not(windows))]
+    #[cfg(unix)]
     pub fn set_mode(&self, filename: &str, mode: u32) {
         let path = self.plus(filename);
         let mut perms = fs::metadata(&path).unwrap().permissions();
@@ -1535,7 +1542,7 @@ pub struct UCommand {
     stdout: Option<Stdio>,
     stderr: Option<Stdio>,
     bytes_into_stdin: Option<Vec<u8>>,
-    #[cfg(unix)]
+    #[cfg(all(unix, not(target_os = "fuchsia")))]
     limits: Vec<(rlimit::Resource, u64, u64)>,
     stderr_to_stdout: bool,
     timeout: Option<Duration>,
@@ -1698,7 +1705,7 @@ impl UCommand {
         self
     }
 
-    #[cfg(unix)]
+    #[cfg(all(unix, not(target_os = "fuchsia")))]
     pub fn limit(
         &mut self,
         resource: rlimit::Resource,
@@ -1956,9 +1963,9 @@ impl UCommand {
 
         let mut captured_stdout = None;
         let mut captured_stderr = None;
-        #[cfg(unix)]
+        #[cfg(all(unix, not(any(target_os = "fuchsia", target_os = "redox"))))]
         let mut stdin_pty: Option<File> = None;
-        #[cfg(not(unix))]
+        #[cfg(not(all(unix, not(any(target_os = "fuchsia", target_os = "redox")))))]
         let stdin_pty: Option<File> = None;
         if self.stderr_to_stdout {
             let mut output = CapturedOutput::default();
@@ -1993,7 +2000,7 @@ impl UCommand {
                 .stderr(stderr);
         }
 
-        #[cfg(unix)]
+        #[cfg(all(unix, not(any(target_os = "fuchsia", target_os = "redox"))))]
         if let Some(simulated_terminal) = &self.terminal_simulation {
             let terminal_size = simulated_terminal.size.unwrap_or(libc::winsize {
                 ws_col: 80,
@@ -2038,7 +2045,7 @@ impl UCommand {
             }
         }
 
-        #[cfg(unix)]
+        #[cfg(all(unix, not(target_os = "fuchsia")))]
         if !self.limits.is_empty() {
             // just to be safe: move a copy of the limits list into the closure.
             // this way the closure is fully self-contained.
@@ -2994,7 +3001,7 @@ pub fn whoami() -> String {
 /// - path: The filesystem path to the PTY replica device
 /// - controller: The controller file
 /// - replica: The replica file
-#[cfg(unix)]
+#[cfg(all(unix, not(any(target_os = "fuchsia", target_os = "redox"))))]
 pub fn pty_path() -> (String, File, File) {
     use nix::pty::openpty;
     use nix::unistd::ttyname;
@@ -3646,7 +3653,7 @@ mod tests {
             .stdout_is("unlimited\nunlimited\n");
     }
 
-    #[cfg(unix)]
+    #[cfg(all(unix, not(target_os = "fuchsia")))]
     #[test]
     fn test_application_of_process_resource_limits_limited_file_size() {
         let unit_size_bytes = if cfg!(target_vendor = "apple") {