A lot of times when a game isn’t listed as ‘playable’ on Steam, it simply means that particular game hasn’t been tested yet, and will probably still work just fine if you actually try and run it. The only real exceptions to that is games that require ‘kernel level anticheat’.

Edit: Check those games out on protondb and see what that says. Since it’s a ‘crowdsourced’ platform, it’s often more up to date than Valve is.