Probably not much since there is already an SDL/OpenGL/POSIX backend which compiles in Cygwin with CMake and is the basis of the macOS port, but I don't have a Linux machine to develop on or test it on so I'm not sure what else is needed.
If you're interested in testing or contributing to a Linux version, please comment on issue #2 on the GitHub page.
If you could provide an alpha Linux build I'd love to try and see if what you've got currently works on my Steam Deck (even if I can't personally contribute to making it work as such outside of reporting what happens). I'm too much of a novice to compile it myself. I'm stuck on "The heck do I do with SDL2?" lol. I tried running the normal version as a non steam game on different Proton versions and got white screens.
