Eh, I don’t really think that this is an “or” situation. I think that this is an “and” situation. The last time that I set up Xash3D FWGS, I had to copy files from the version of Half-Life that I own on Steam into a different folder so that those files could be loaded by Xash 3D FWGS. I haven’t tried Xash 3D FWGS in a while, but it looks like you still have to do that [1]. Also, are you sure that the Steam version of Half-Life is Windows only?
For whatever reason, Valve doesn't want to open source the engine so some people have taken it upon themselves to build a reverse-engineered engine (which now runs on Android, in the browser etc).
Valve updates HL1 every few years so it runs on contemporary platforms. DOS was ancient history by the time HL came out, you might be getting it mixed up with Quake1
Yeah Apple's latest round of breaking changes hasn't been addressed (and seemingly won't be).
The Linux and Mac ports happened in 2013 or so (presumably getting one working went a lot of the way to getting the other working, though there is some speculation that Apple poured in some money to help make it happen).
Later it became clear why: the Apple Silicon transition, and Rosetta 2, which is optimised for running x86-64 binaries on Apple's Arm64.
But the same change is looming on Linux: Ubuntu tried in 2019 but was persuaded not to, Fedora has tried more than once.
WINE 11 can run Win32 binaries on a pure 64-bit host OS without 32-bit libraries. So, you can run some 32-bit Windows games on 64-bit Linux and macOS which cannot run the 32-bit binaries of their own older versions.
Apple merely jumped first. I think it's not to be blamed here. It'll happen everywhere in time.
