>>The caveat is that this is only true when applied to games on Steam. I play games that aren't on Steam, and I've not even bothered to see if they would run on Linux because it's just not worth my time.

I play Diablo 4 on my steam deck and it's so little effort to install it - you install Lutris, install battle.net and then it just works, you can launch it directly from the Steam Deck UI.