The only pain point I've found is VR. I've bounced off trying to get it working multiple times with the best results getting about 10% functional (video working on one or two games, input broken on all).

That said, I haven't tried getting the same kit working on windows so I can't say if it's any better.

VR is rough at the moment, but one would hope that Valve is prepping an overhaul for SteamVR on Linux since they're launching a standalone VR headset which runs Linux soon.

I ran into the issue where I didn't know that you can tell Steam to always prefer NATIVE LINUX programs over everything over Proton. This was causing a ton of issues with VR, I havent gone back to try it yet though, havent found the time.

It was very broken for a long time. Since fairly recently you have WiVRn (specifically wivrn-dashboard on Arch) for Oculus (more supported though) and I would daresay it works better then SteamVR used to do for me on Windows

Hardware for flight sim games is also in a similar boat. It's hard to configure most of the newer hardware, but a lot of the old low quality joysticks work alright out of the box.

I have both a Reverb G2 and a Pimax both working great via Monado.

or DRM for old games that check stuff like the cd being present

I have owned the index for a few years, running it on ubuntu/mint. It is a pain. But VR is a pain generally. I go months without using the thing. Then when i do use it some bit of software has been updated and i inevitably have to spend an hour getting it to work correctly again. Honestly, VR on linux feels like using windows again.

VR is bad because nobody cares much about it. The hardware is clunky, the market tiny, and costs great. As the hardware improves it will get more attention from the FOSS community and so too will the overall experiance.