I just claimed the Steam key to see the differences in the game on steam. I'm on Steam for Linux, and currently, my PS5 controller does not work while playing the game in Steam. If I play the stand-alone Linux version it works great. I have tested other games in Steam and controller support is there for them, so I think I found a bug. The hard part is determining if it is a Steam bug or a periphery bug.
I know I have said this before, but it is worth repeating. This game totally rocks!