As people have said, you can add Jellyfin as a service to start with windows regardless of users being logged in.
No one seems to have said how to do this.
The easiest way is to use the NSSM open source tool - it stands for “Non Sucking Service Manager” and it gives a GUI route to create services, as well as some useful reliability and fall back functions.
It can also be used from the command line if you prefer but regardless it’s probably the easiest way without faffing around with powershell or command line and in built windows tools (which do suck).
Edit. The official website is NSSM.cc and it includes guidance on how to use it. There are also plenty of guides online if you search “how to create a windows service”.
Edit2: the easiest way is to use the Jellyfin windows installer itself but the documentation is pretty vague on that and gives a warning about ffmpeg config. It should work but using NSSM will give you more direct control. I think the installer uses NSSM anyway.
Sony bought the studio, Sony published this, and so Sony effectively greenlit it. Sony corporate then? This was not an independent game developed for PS5, this was in house.