Thanks for trying it out on steam deck!
Yeah I added controller support and worked quite a bit on it but I'm still usually testing my game with mouse+kb, and I added controller support to some parts of the game (lockpicking) just before posting the demo here.
I realized the culling was turned on in my game but I didn't add any occluder geometry to my level, so expect the game to run better in the coming months. I also got frustrated trying your game out at how well I was able to tell where other players were around me compared to mine and found out I had almost no audio panning on.
The unrendered sprite that billboards towards light sources could be cool, I'll try it out