Nice post! I would like to add I personnally had issues with heroic launcher for it to recognize the steamdeck inputs (in my case LotR:Return to Moria, from Epic. I tried Heroic and Lutris, Lutris is my go to on desktop). My solution was to launch the games from steam after adding them with this.
I did not lose anything since the game is runing well and I got it for free. The game does have some weird things going on and miss some features indeed but as long as I can have fun with friends…