These days you can do that on fucking arch (from the point of “have a usable DE with internet access” onwards ofc, which is the point most distros get you out of the box). Install steam, check the setting to show windows games with proton, and it just works. At most need GEProton sometimes but I doubt that’s different on SteamOS.

No doubt SteamOS is the most optimized for that experience but there really isn’t a lot of friction for gaming on steam in general these days.