I might be remembering incorrectly, but didn't the Frame support foviated streaming not rendering? As in, isn't foviated rendering a game specific thing, not a headset specific thing?
With 3 drives I would go with BTRFS RAID1. You get half the capacity, can lose any one of the drives, and it is really simple.
If you were to add drives later on to increase the array size, I might consider RAID10, but if you plan on sticking with 3 drives, I would go with RAID1 instead.
Rootless podman caddy doesn't need those priviliged ports, if you have your server behind a firewall device. You can map your ports on the firewall/router 80:8080 and then on the caddy container 8080:80. This way there is no need for priviliged ports and the traffic seems to go on ports 80 (and 443 the same way).
PostmarketOS has piqued my interest as the most promising Linux phone OS. I would give it a try if you can put up with an immature system, at least when compared to Android.
Filebrowser quantum is really good! Easy to setup and use.