I got my OLED yesterday and so far all three HDR games I’ve tested (Tetris Effect, THPS1&2 and modded Control) won’t allow HDR to be enabled. I cant see any workarounds for them so far either. Hopefully this will be improved with time, but as a start it seems HDR support is about as annoying as it is on desktop PC!
To be expected, HDR on linux is super new
I would expect developers and valve to improve upon it over time