I’m a home-lab newbie but I built a NAS & Jellyfin server with a Raspberry Pi 5 and it works great. I got a SATA hat for it and it has 5x 8TB HDDs installed with ZFS RAIDZ1 in a custom 3D printed case. It can stream 4K on my network just fine. If there are other tasks you want your server to do I’m sure other people would recommend something more powerful but I just wanted to add my 2 cents. I picked up another Pi to set up tail scale (work in progress) and yet another Pi (open-box discount) to set up Immich (near-future project). I wouldn’t expect one Pi to handle all of those things simultaneously but I haven’t tried it.