Yes that seems to be the consensus in the end. Thanks for your answer :)
For the docs I've found this for Proton common issues: https://partner.steamgames.com/doc/steamdeck/proton?l=english And this for Steam Deck compatibility: https://partner.steamgames.com/doc/steamdeck/recommendations I'm sure there are other resources, but if someone finds the thread later and needs a starting point, here they are
The initial goal was Steam but it looks like some people prefer GOG so I'll study that possibility too :)