I'm using a QD-OLED monitor and love HDR for movies or tv shows but with gaming I have several gripes that don't make me enjoy HDR as much, funnily none of them caused by Linux.

A lot of games suffer from pretty terrible HDR implementations so it might just end up looking worse than SDR. Additionally, at least on this display tech, HDR is a trade-off between stable brightness (TrueBlack mode) or peak brightness (Peak mode). I find TB mode to not really pop enough to justify HDR, but peak mode to be too distracting for gaming since turning your camera can quickly change the overall brightness and make the image flicker.

I would say in theory HDR could be a huge increase in immersion for gaming but the tech and execution isn't really there for me yet.

HDR support on Linux though I find is in a pretty good spot if you're not opposed to setting a few env variables.