I'm using a seedbox and I can access it from anywhere, just fine. I'll be honest, I'm not sure about the implementation details, but I'm pretty sure it's done via a reverse proxy like so: https://jellyfin.org/docs/general/networking/caddy/
Wow. No idea this existed. I was about to set up a TV tuner with my Plex and pay $4.99 for the ability to broadcast live TV over Plex but see that JellyFin has this feature for free.
I switched a year ago after some dumb monetization change at Plex annoyed me enough and it's just been so much better.
Imagine a product just like Plex, but without all the shit Plex tries to pull all the time!