I don’t know if it would give you as much hard drive space as you want, but I got an Odroid HC4 a while ago and it’s been great. One of the very few SBCs with two SATA slots ready to go.

Buco seems to be having a good time. 9/10, unsure how Eaton feels.

Just cleaned mine up a bit recently!

PC on the left, RPi for simple stuff and an Odroid HC4 as my media and backup server.

Not pictured: another RPi dedicated to HomeAssistant, a magic mirror, and networking stuff.

Also not pictured: my workbench tools on the upper shelves, which have not been tidied recently.

I’ve used Armbian and DietPi. Currently running a magic mirror on a Rock64 and a NAS on an ODROID HC4. Of the two OSes, I think I’d recommend Armbian. Skip installing a DE and just get a basic X session with a simple web browser.

Note that MagicMirror is web based, so the setup steps for putting up a web browser would be similar.