Valve has been Linux friendly. It says the new steam frame “is a PC” and will run Steam OS but I feel like there’s an insinuation that, like the steam deck, you can install whatever you like. I am cautiously excited at the premise of really digging in and having a Linux box strapped to my face.
Another friend has already referred to it as the Linux Vision Pro.
Edit: watching Linus tech tips review, it mentions side loading Android APKs as well
Just about every big distribution has an ARM build. And most open source Linux apps build for ARM as well. In that regard Linux is much better set up than Windows.
The emulator FEX isn’t part of Proton but of course it is integrated with Steam similar to Proton.