Yep, that’s why I call that a tradeoff. Far from perfect and yet so much better than nothing.

Pros:

• Likely cuts 99.99% of attacks.
• Nothing to do on client’s end.

Cons:

• Whitelisting must be updated everytime the client address changes.
• Not 100% bulletproof as operators (notably for mobile networks) can NAT multiple connections behind a single publicly addressable IPv4 address.
• Also IP addresses can be spoofed but I doubt that would be a major concern here.

No, not for remote access over the internet.

For a remote and non-technical user I would say IP whitelisting offers a decent tradeoff.

On your end you expose your jellyfin port to internet, but restrict at the router level to your user’s client IP address as soon as you have it. Obviously in practice this works best if the address does not change often.

I have searched for such a game, featuring both realistic driving and open world roaming.

I settled on BeamNG.drive which can do that out of the box, even though it’s capable of much more. While it lacks the high quality environments of the Forza Horizons it has very good wheel and even VR support and is simply the best automobile sandbox around.

Oh so there is a proper name for this ! I have had those once in a while since I was a kid, and still get them well into my forties.

I do still remember the anxiety the first time it happened.

I like the enthusiasm, but I’m sure you realize why Jellyfin is more suitable for mainstream use. The pretty web UI, user management, watch tracking and device-specific clients are what makes the software actually useful if you want to serve media to “normal” people.