I know telling you that “You should have done this” isn’t helpful today, but super recommend Proxmox in the future. I have had containers running Plex, Jellyfin, and Emby all on the same physical host by utilizing LXCs. Migration could be rough, but overall it’s not as complicated as it sounds.
Jellyfin doesn’t really do anything better than Plex. If someone already does have a Plex pass, then the best you can say about Jellyfin is that you’re glad things are missing (Like Discover/Plex Channels/etc). Also, the level of support for Jellyfin just isn’t there. Plex doesn’t always have great support, but answers to technical problems in Jellyfin are frequently just “Don’t do that”. As others have mentioned too, the experience of sharing your library with isn’t really even comparable. Your chances of sharing your Jellyfin library with your grandma are near zero unless you just do it for her.
The process of setting up Jellyfin as a backup solution actually led me to experimenting with Emby. Unless something crazy happens to my current Plex implementation I’m still not going to proactively switch, but Emby legitimately does (rarely) have some features where it has a leg up on both of them.
Not misunderstanding, just not the full picture. Proxmox can do VMs, but LXCs are different thing.
LXCs are a ‘container’ and have some requirements that might be frustrating sporadically, but they are much lighter. They’ll present like you’d expect from a VM (Their own operating system/shell/etc) but resources are mostly shared across LXCs on a host. Overhead isn’t gone, but drastically reduced. Personal experience obviously, but it’s never been something I’ve had to seriously consider on an LXC.