I buy games for my steam deck, only stopping to read up if they're "unsupported". Surprisingly, they seem to often STILL work in that case, this happened with Ghosts of Tsushima, which was unsupported because their online play didn't work (good riddance lol).

Never had an issue with any game running through proton. Only issue was Stardew Valley that couldn't play online. Turns out the Linux version (was default) had an unfixed bug, and choosing the Windows version with proton "Just Worked". Hilariously, "Win32 is the most stable Linux ABI"...