That may be true, but how do you grant non-technical family/friends access? They don't even understand what a VPN is, let alone how to toggle one on/off to access the Jellyfin instance.

Additionally, if they try to connect from an Android TV / Fire Stick, where you can't configure a VPN (and use their ISP's modem, so no wireguard client on the router to transparently route to the subnet), what are you supposed to do?

I feel it may be easier long-term to just contain the Jellyfin daemon to only r/o access to media, putting it behind a subdomain like jellyfin.example.com, and use the dns-01 challenge via LE to only provision a wildcard cert for the domain (IE *.example.com).

Then, have nginx listen on 80/443 with a default server directive that returns 444 for any requests not to the (correct) jellyfin hostname (due to bots hammering 80/443 across the internet on webserver's direct IPs).

Its the only solution I can think of to make it easy for nontechnical users (everything just described is completely invisible to a regular client) while reducing the attack surface area of the daemon.

FWIW, with the aforementioned setup, I got 0 unauthorized requests to my jellyfin server. Just a bunch of bots hammering my IP's 80/443 ports directly with exploits for old (usually wordpress) vulns, but they were all served 444 (IE an immediate TCP connection close without nginx even responding to the request).