You’re right, it’s not “just” Proton. I also tried recently GoG for Pod and… it just worked! From buying the (sigh) Windows game to playing on Linux in literally minutes. Amazing.
For WMR I don’t know unfortunately. Monado does work though and I would check https://lvra.gitlab.io as it’s a great starting point, maybe starting with the Monado SteamVR plugin.
I hope I won’t undermine your entirely justified trust but Altman is also a crypto guy, cf Worldcoin. /$