I don’t disagree, and I am one of the VPN advocates you mention. Generally there is no issue with exposing jellyfin via proxy to the internet.
The original question seemed to imply an over-secure solution so a lot of over-secure solutions exist. There is good cause to operate services, like jellyfin, via some permanent VPN.
I would not publicly expose ssh. Your home IP will get scanned all the time and external machines will try to connect to your ssh port.
Over the top for security would be to setup a personal VPN and only watch it over the VPN. If you are enabling other users and you don’t want them on your network; using a proxy like nginx is the way.
Being new to this I would look into how to set these things up in docker using docker-compose.
You hit the nail on the head.