It’s not Jellyfin, but here’s my N100 simultaneously doing two 4K HDR transcodes with tone mapping enabled. Neither stream had buffering.

So it’s definitely a capable chip, but might be dependent on transcode settings.

Nginx is a lot less painful if you use Nginx Proxy Manager. You get a nice GUI and can easily get SSL certificates with Let’s Encrypt, including wildcard certs. I’m running it in front of a docker swarm and 3 other servers, and in most cases, it takes me about 30 seconds to add a new proxy host and set it up with https using my *.domain.com wildcard cert. I also use it with Authentik as a forward proxy auth for SSO (since many containers out there don’t have the best security).