If anyone wants to play Doom with GZDoom and easy mod access, I’ve been doing that for a while via Luxtorpeda.
Add it to your compatibility layer list like you would ProtonGE, then choose the Luxtorpeda compatibility layer for DOOM. Once you launch it you can choose either straight up GZDoom or qZDL+GZDoom for easy mod management.
Have you personally tried Boxtron or Roberta on the Deck? I briefly messed around with them a while back, but at least at that point it wasn’t as simple as just installing them via protonUp-qt or WineCellar.