[roxil]

I also have a Steam Deck and still prefer buying games from GOG, when possible. Heroic Launcher is a nice GUI that let's you easily install GOG+Epic store games, sets up the proton stuff and gives you the option to add the games to Steam as non-Steam games.

[Fire-Dragon-DoL]

I tried, but it doesn't seem be anywhere near the simplicity of buying games on Steam.

Not to mention, it needs double the size of the game when patching (with baldur's gate that's like 180 GB)