Even with docker, things can get complicated. Like if you use *arr stack for your plex library, but you manually copied in some extra subtitle files, or tweaked the descriptions of some media. Now you have to find those customizations so you can migrate them to the jellyfin library
I just set it up with my Docker setup. Point it at the appropriate volumes and it pretty much goes. GUI tools for Docker help. I like Dockge.
Even with docker, things can get complicated. Like if you use *arr stack for your plex library, but you manually copied in some extra subtitle files, or tweaked the descriptions of some media. Now you have to find those customizations so you can migrate them to the jellyfin library