My main source regarding the privacy/security stuff is this blog (in German). To be clear, /e/ isn’t bad on that front, the alternatives are just better.
You can read mode on the OpenAI integration in the /e/OS forums and the fairphone forums.
/e/OS is just another android rom, and unlike calyxOS or grapheneOS, /e/OS isn’t very privacy focused. There’s some weird stuff regarding a hidden “license id” and some of their services rely in openAI. You might as well just use a “real” privacy-first android rom if you’re trying to get away from tech giants, their tracking and closed source software.
Regarding oculus software: If you need the actual oculus software for some reason (say, if you’re using a rift S) your only option is a windows VM with full access to your GPU (and possibly your USB controller), either via looking glass or single GPU passthrough. Both options are a little hard to wrap your head around and annoying to set up but I’m sure your favorite search engine can help.
As other comments have mentioned, ALVR and SteamVR are solid options of all you need is the “screen sharing” part.
CalyxOS development is paused right now but it’s still available and campatible with more devices. I wouldn’t recommend a currently unsupported OS but personally I’m still using it on my Pixel 7a. I had some google integration issues in GrapheneOS, plus I prefer the focus on privacy instead of security.