Unsurprisingly, the Makefile did not work for OpenBSD either.
I had to use gmake and change the Makefile around (as per what was done for FreeBSD) to get it to compile and install.
Also had to remove the she bang at the top of the python script, along with the "where ... exec" lines and just replace the shebang with default python install dir of #!/usr/local/bin/python3
After doing this all worked as planned!