I got really into the idea of making a home server setup after watching HardWare Haven's videos, and this is what I ended up with! A generic PC from over 10 years ago with some random hard drives inside.
I first started out with Ubuntu Server, with CasaOS on top of it, but quickly ran into walls (mainly in configuring drives), so decided to just switch one of the dedicated Server OS things I saw people talking about. OpenMediaVault gave me a really bad time and Unraid cost money so I settled with TrueNAS Scale. It took some learning and fiddling to get containers set up, but it's all good now!
I have 3TB of redundant storage for personal files (camera backups, old projects etc), and 1TB of vunerable storage for my Media (mostly DVD and Blu Ray rips). I tried out Jellyfin but the poor CPU couldn't handle it (besides, I don't really need a fancy frontend, I'm fine just looking for the files in finder and watching them in VLC, which works great!)