Thinking of switching to windows or truenas for a new jellyfin build

[bitmap]

continuing on, docker is already installed with ubuntu, I can just install portainer from there, create directories, populate them with media, do the pull for jellyfin and point it to my directories get it all configured and then just leave it alone for months on end?

Pretty much. I think what comes with Ubuntu is a different version of docker than I'm used to, so I always end up installing it manually (I use apt, not snap) but the snap version should work. You may need to install the compose plugin. Docker documentation is pretty thorough but it's a versioning hellscape of confusion. Luckily their install info is solid.