It's important to note that Apple cut off the Proton devs; not the other way around. It would indeed be pretty cool to see that sort of thing running on Apple Silicon, but the plethora of architectural changes that came along with Catalina stopped Mac support from being a viable target for Valve.

Not very surprising though; Mac native games don't really work that well either. If it relies on 32-bit libraries, it won't launch. If it uses outdated OpenGL, you can expect a plethora of errors to accompany you to an instantaneous crash. Apple has their work cut out for them, I just doubt they'll have the "courage" to bring back the features they so courageously threw away.