I’m sorry to hear you’re having trouble!
Regarding the vainfo thing, at least on Arch, the Nvidia vaapi driver is a separate package. I’m not sure what the equivalent is on bazzite, but that’s likely why vainfo doesn’t show anything. And you should still be able to use nvenc anyways, which sunshine will choose before vaapi.
Is moonlight able to see the computer on your network? And in sunshine’s web interface under the “troubleshoot” tab, there’s a log. Does it say anything that might help?
From my experience, phasmo’s proximity chat works in-game, but not in the lobby.