The only stuff that is completely broken is Easy Anticheat and BattleEye, but those will supposedly be working when the new Steam Deck starts shipping.
Side note: if you end up dual booting your gaming PC, please learn from my mistakes and disable Fast Startup before you do. Otherwise you're going to have a bad time.
Lutris ( https://lutris.net/ ) also provides scripts for games that aren't on steam or bought on other stores.
You can also install Pop!OS which is another Linux distro for gaming (or so I've heard).
For anyone interested:
From what I've gathered, Pop!OS has a bit more support than the officially released SteamOS Beta version, which is actually someone outdated right now. But from what I've read about the Steam Deck, Steam has a new version of their OS that the deck runs on. So maybe (hopefully) it will be released along with the deck - couldn't find any info on that though.
Valve has stated that their SteamOS 3 will be a freely-available open platform, and that they encourage other device manufacturers to ship it on their hardware. I assume that this means isos will be available.
Having had similar problems (not just windows, RDP/VNC/you name it) to me this now sounds like 'wrong tool for the job'; just use e.g. Anydesk : no install, just an exe, have the remote side run it and tell you the ID and you're good (at least it didn't fail me once yet). From then on configure RDP/VNC yourself, and the router's port forwarding, etc.
After several...frustrating...hours of trying to talk them through things over the phone to get RDP working, just so I could install Docker to run some containers that didn't even work properly with networking, and having to call/text any time the machine thought it was smarter than me and rebooted because of an update, I finally drove out there, wiped it, and threw linux on it (Ubuntu 20, which serves the purposes I need).
The entire installation process took about 15 minutes because I was explaining it to my dad as I installed it. Zero headache since it was plugged in next to the router and powered on weeks ago, and the performance on the running containers makes it feel like a brand new computer compared to trying to run them in Windows.
I run a Windows desktop locally for gaming. I've heard good things about SteamOS and have been toying with switching, but I'm put off by the idea of trying to re-flash Windows if it doesn't work. Personally, I'll be happy when I no longer need Windows even for gaming.