Well fair, you can install both at the same time. I installed Plex again earlier today and it was wat easier this time.

What’s the issue with using your phone logged into your account to authenticate on the TC?

You can use your phone to login to Jellyfin these days and depending on the TV and app you can have a profile switcher. You can also make a passwordless account. Which would be fine if you used some other form of authentication.

You just give those people the name of the app your recommend (Jellyfin, Moonfin etc) and give them the URL and their username, then they create a password.

It’s not that difficult for most and if it is you help them once with it.

Plex doesn't have hardware transcoding unless you pay almost 800 euro

No you are right, it is 800 euro.

Jellyfin is easy to prove you are the owner off. While Plex has issues with that on systems like TrueNas when you don’t have full access to the server

It;'s probably about 800 euro, but that is still 800 euro more than Emby/Kodi/Jellyfin or whatever other altnerative. I had a lot of issues with Plex due to them requiring that proof of ownership thing which didn’t really work on TrueNas core I think it was?

Jellyfin is way easier imo