Alien Isolation itself runs fantastic on Linux. It's Linux native and also runs great on Proton. But the VR version comes from a mod called MotherVR. Trouble is that this mod works by overwriting a DirectX dll. The same dll that Proton needs to overwrite so that Direct3D calls are translated to Vulcan for Linux. And the mod owner vanished about 4 years ago or so, shortly after they announced they wanted to open source the mod. So unless someone wants to replicate their whole work we can't figure out how to make it work in Proton or natively on Linux.
Yeah, it works good enough for the games listed above. I get a slight stutter every few minutes or so. But for now it's been playable. But I doubt that it will be enough to run Alyx comfortably.
I'm using ALVR and a Quest 1 headset. Its lower resolution should definitely help. I tried halving the resolution for Squadrons to see if it could get rid of the stutters, but it didn't help with those and instead made the game too ugly.
One caveat, I'm running OpenSUSE instead of SteamOS. That might give me slightly better performance, at least that's my subjective impression. Games run definitely better on Plasma Wayland than X11. And last time I experimented on SteamOS with VR I couldn't get it to work in gaming mode. And 2GB of zram definitely helped with City Skylines, but the impact on VR-games should be negligible.
Because it's slow and VR is very resource demanding. It has to render everything twice and to mitigate motion sickness, the standard FPS to hit is 75-90.
From NoneYa's comment, it sounds like it "works" but it's not gonna be very enjoyable.
I would only play games that don't require walking around like Job Simulator. While I have gotten used to it sitting or standing, trying to walk around while laying down using the new lay down mode on my Quest hella makes me sick. I mostly just use lay down mode when watching videos.