I’ll start. Did you know you can run a headless version of JD2 on a raspberry pi? It’s not the greatest thing in the world, but sometimes its nice to throw a bunch of links in there and go to sleep.
What you are looking for is a VPN or to port forward Jellyfin. Not to be confused with a Commercial VPN. You want him to Virtually connect to your Private Network. Personally, I don’t trust port forwarding Jellyfin directly. So, I setup a wireguard VPN and port forwarded that. Then, connect remotely through the VPN to the local Jellyfin. Idk about Roku though. I cannot say wether they have a good wireguard app.