Hey, wow, that's quite the collection of issues!

For one, the kernel completely stops responding to even Alt+SysRq+R-E-I-S-U-B when validating my Wallpaper Engine install in Steam and I don’t know why. I found a plug in that allows it to work in KDE but I can’t even get that far if I can’t even install the app. I just ended up not installing it, but I’m still looking for a Linux-native app for animated wallpapers.

This one could be any number of things- one trick for figuring out what the issue could be is to see what your system log looked like right before the hang. You might have to scroll up a bit and there's going to be a bunch of noise from random stuff reporting their status that you'll need to ignore. Look especially for lines with red text and the word "Error". To get the log from the current boot (not the one you're looking for) run journalctl -b, similarly, to get the one from the previous boot (the one that would have crashed) run journalctl -b-1 - you can also look at the logs from boots before that with journalctl -b-2 and so on (assuming your haven't limited the size to the point where those no longer exist).

Secondly, I have this weird flickery-ghosting effect when playing games in fullscreen (Well, actually just Helldivers 2 cause it’s the only game I’ve tested so far). Borderless windowed is fine but then there’s a distracting thin white border around the window.

Just a hunch, but I ran into something similar and realized it was g-sync/freesync (which only runs when an app is fullscreen). The refresh of the game changes the refresh of the monitor, and on my TV it only gets flickery when the framerate is slow (like in menus), while on my desktop it gets flickery in a bunch of situations, so I assume it's just a bad implementation there. Interestingly, I don't seem to get tearing even with it disabled, so I just turned it off.

Thirdly, I can’t even begin to comprehend how OpenRGB is supposed to work. It’s like trying to understand a foreign language, especially given how intuitive and easy to use SignalRGB is (Windows exclusive). I can’t even figure out how to use OpenRGB to simply disable the damn lights so I don’t have to deal with it.

Haha, oh man, yeah, I personally just wanted to turn off the lights on my RAM, and iirc deleting items was pretty easy though I'd have to check to see what I did to remember exactly how it's done (let me know if you want me to take a look). Trying to configure stuff to light up a certain way is an adventure I haven't attempted to tackle yet.

Fourthly, the Nvidia X Server app is missing almost every single feature that Nvidia Control Panel has. Where are the 3D settings for games? Where’s the AI stuff? Where’s RTX Video Super Resolution? I didn’t spend $1800 on a GPU, only to not be able to use it to its fullest.

A lot of the fancier consumer features end up lagging behind in terms of support on linux. I personally hate how AI makes videos look and I use AMD which doesn't have those fancy features in the first place :), but I can see how you'd be annoyed not at least having the option. I think all of the nvidia features games utilize are supported, but a lot of the stuff you'd normally need to open up the graphics card configuration tool on windows to access and configure is likely going to be missing. At the same time, there are quite a few CUDA-based AI tools out there that you can use on linux that would be a pain to set up on windows, so you lose some things and gain some others. The ollama-cuda package on archlinux is a fun place to start.

And most importantly: HDR is completely broken, which is a show-stopper for me. I’m too used to HDR to go back to SDR, especially in movies or games. Turning it on makes the desktop and all SDR content look dull and washed-out on an LG C1 OLED, like a faded photo from the 1970s. It’s obvious that KDE isn’t properly mapping SDR colors to an HDR space. The SDR color intensity slider does nothing, either. HDR works perfectly in Windows 11, even when showing SDR content.

That's really odd- I'd seen examples of that being the case before KDE 6 was released, but when I first tried it on with my LG G3 (so pretty similar to you) I found a good slider brightness position and everything looked great from there. I wonder if it's an issue of nvidia vs amd or something else?

tl;dr: I don’t actually expect any help; just wanted to vent. I’ll figure this shit out eventually, but until then, I’m dual booting Windows 11. From what I understand, HDR support is still in its early stages for KDE. So I’ll check back again in a few months to see how things have improved. Anyway thanks for listening.

Haha, well I did my best anyway :) After your experience I can't really blame you for dual booting (and probably mostly sticking to) windows 11 for now. If nothing else, you can keep your linux install around to occasionally check and see if the caveats have dwindled enough to start using it more regularly eh?