Your head might be spinning from all the different advice you're getting - don't worry, there are a lot of options and lots of folk are jumping in with genuinely good (and well meaning) advice. I guess I'll add my two cents, but try and explain the 'why' of my thinking.

I'm assuming from your questions you know your way around a computer, can figure things out, but haven't done much self-hosting. If I'm wrong about that, go ahead and skip this suggestion.

• Jellyfin good - a common gateway drug to homelabbing, and the only thing you'll do that non-tech friends will appreciate
• Proxmox good - it makes the backups simple and provides a path forward for all sorts of things
• Docker good - you've said it increases complexity; this is correct in that you're adding more layers of stuff, but it reduces your complexity of management by removing a heap of dependency issues. There is a compute and memory overhead involved, but it's small and the tradeoff is worth it.
• VM good - yes an LXC is more efficient, but it's harder to run docker in. Save that for a future project
• Media data somewhere else good - I run a separate NAS with an SMB share. A NAS in a VM is a compromise, but like all things self hosting, you start out with what you've got. I let Jellyfin keep the metadata in the VM that's hosting my Jellyfin though since the NAS is over the network. That's less of a consideration if you are visualizing your NAS on the same machine, but I'd still do it my way for future proofing.
• Passthrough magic not yet - this can also be a future project. If your metal has quicksync that can be utilized to reduce the CPU load, but that can also be a future project.