I’m on a much weirder setup than you’re proposing — Bazzite Linux with a Pico 4 connected wirelessly via ALVR — and it mostly just works. I had to jump through a few hoops to get everything working to start, mostly related to tweaking wireless and audio configuration, but these are things I doubt you’ll encounter at all with an Index. I haven’t tried a game yet that doesn’t work. I mostly just care about Beat Saber and a couple of others, but they’re all working well. I’ve even bought a few new games since switching to Linux, and I can’t recall any I’ve tried that don’t work, out of maybe a dozen or so total I’ve tried. I suspect you’ll have a much smoother experience with the Index.

I’m using ALVR with a Pico 4 headset on Linux, and it’s pretty solid. I’m not playing a ton of VR games, but so far I haven’t found anything that doesn’t work. It has some quirks, but it works pretty well. I’m very happy with it.