Yes, you could do something like keep a small root fs or pack everything into the kernels paqfs to boot into a Tailscale VPN and pull root from another 9 machine on the VPN. Then pull resources in from other machines including non 9 systems.

Either way it makes VPN easy between 9 and non 9 machines. Otherwise Plan 9 can do it's own VPN-like over tls or ssh tunnels and bind remote network stacks to a local namespace. But that makes seamless Unix and Windows comms difficult.

I think so! Caveat is I've never really used Plan 9 outside of single-user VMs.