I wrote up a guide [1] on using Plex + Tailscale + HTTPS last year to setup Plex so you don't have to expose it through the Plex relays or setup port forwards for other devices on a Tailnet.

I would assume with this announcement, you can keep Plex private to your Tailnet and an AppleTV also on the Tailnet could use it without any port fowarding.

1. https://forums.plex.tv/t/remote-access-using-tailscale-magic...