I have a small apache case from harbor freight with a LePotato, mini router and a battery in it. I intended it to mainly be a road trip jellyfin/emby server (still deciding on which to fully implement) but I also have kiwix, Audiobookshelf and a simple nginx webpage to make getting to the services easier.
I've got 10 12tb Seagate EXOS drives in operation right now and have also run small capacity (2-4tb) WD Red and blue and Seagate Barracuda drives. For ssds I run Samsung 870 evos.
Been considering building a mini lack rack to put on top of my lack rack to hold my mini PCs.
My cold storage is another Truenas box that powers itself up once a month, pulls an rsync and shuts down 2 hrs after that completes. Not quite what you asked for, but I don't have to think about it. The drives in that server are the smaller drives (2-4tb) that have been in the main Truenas box and been retired from that duty.
right now just the Amcrest app. Eventually I want to add more cameras and set up a NVR.
I have a media server built in an Apache 1800 case with four 2tb 2.5" ssds in it.
If I where doing this, I would fill a hard case with nvme drives or 2.5" ssds and put 4k remuxes if you're dead set on 4k, or 1080p remuxes, the ones on my server are 6-8 GB. Yes, you can get super high capacity ssds, but they are real expensive. The reason I have 2.5" drives in my box was price. I paid $50 for each one.