I wouldn’t say we’re over-reliant on Steam, but maybe on Valve to some extent.

If Valve would suddenly stop all their work on/around Linux, that’d certainly affect Proton and also things like the open AMD GPU drivers. Sure, others would likely continue their work (it’s not like they’re doing it all alone now anyway), but Valve certainly brings a lot of expertise and also commercial interest.

Would be awesome if you’d share your solution for the next person encountering the same issue :)

What exact GPU model? Kernel version? Have you tried it with SELinux disabled temporarily?