Plex probably isn’t the best example, but yes, you can use Tailscale to create a sort of mesh network to access devices within private networks. Essentially any device that’s connected to tailscale can be contacted by other clients connected to tailscale. There are extra routing things you can do to use a tailscale device as a sort of “exit node”, but that’s the basic gist.
Subbed. Just curious as to how (or if) you intend to differentiate yourself from the Jupiter Broadcasting team’s Selfhosted.show podcast?