In this scenario, your dad just installs Jellyfin and logs in.

You've set up the reverse proxy to your server, its transparent to him.

You can update DNS records automatically so its also a fire and forget kind of thing.

But I guess, give your data to the corpos because its easier.

Which part? For the TV there was literally a wireguard app. I just had to install it on the TV and configure the connection to my wireguard server.

For the bridging I gave her my old router which I haven't tested but I believe should support VPN bridging. I already have her on a subnet that won't conflict with my network for that reason.

That doesn't slove the problem if your Smart TV doesn't support tailscale or something like Wireguard. Using another machine connected to a VPN like for example Tailscale/Headscale and then using ssh portforwarding allows you to access the service(jellyfin) on the device without support.

It would be like this:

Jellyfin <-- Tailscale/Headscale <--- Machine forwarding the jellyfins port <-- Smart TV

This can be done with a command like this:

ssh -L 0.0.0.0:8096:jellyfin_tailnet_ip:8096 -f -N user@machine

I set up a free dns from duckdns.org and pointed it to my jellyfin server. All my parents had to do was to use that https://randomserver.duckdns.org/ as the server url in the jellyfin app.

Yeah then this might not be a great idea for you, unless you have the possibility to fix a machine if you visit. But I want to make it clear this is not a fix all thing just trying to help :D