the last 32bit only Mac system shipped a decade prior to Catalina. 32bit was dropped a decade after support for the last 32bit only Macs. Apple Silicon in both iOS and Mac is 64bit only, on iOS it has been for years.
Despite that, macOS supports everything required for proton - the mechanisms that allow wine to run 32bit x86 apps on both intel and under rosetta exist pretty much purely for the purpose of things like wine (and so proton).
So I'm not sure where you get "apple cut off the proton devs" from that work
It was quite odd because the original herald of Steam Play had macOS front and center, even with exclusive cosmetics if you launched the game on macOS.
I do remember a large kerfuffle over the very poor state of OpenGL on macOS, which if I remember correctly was stuck on 3.2 for a long while, before being completely deprecated.
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 If it uses outdated OpenGL, you can expect a plethora of errors to accompany you to an instantaneous crash.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.