I've tried several strategies, but none truely works.
Here is the repo/file that demonstrates the issue: https://github.com/EugeneLoy/ghp-test/blob/main/README.md
Url to Github pages of this repo is: https://eugeneloy.github.io/ghp-test/

[1] works fine, since there is no space in filename.
[2] works on Github pages url, but does not work in Github UI, since it does not adhere to GFM (I guess).
[3] - [7] all fail to work on Github pages url (some of them work in Github UI though).

I am not sure whether this behavior is a bug or what I want can be classified as feature request, but I would like to know how to achieve links to .md files with spaces in filenames that work both in Github UI and on Github pages. If there are some workarounds that can achieve this - I would also like to know.