

Really depends on what you want out of the system, what you can spend and how much time you want to spend on it.
My old z390 itx system has a 16x PCIE to 4x m.2 card - leveraging an m.2 to 5x SATA adaptor with the built in SATA adaptors has given it plenty of space.
Considering I can grab m.2 to 6 SATA adaptors and fill the remainder of the slots that’s a decent chunk of drives from a single PCIE x16 slot.
Software is another kettle of fish and a good way to timesink, I’d rather not give too much of my personal experience as there are so many ways to skin that cat.
In love with Syncthing. Does my keepass database across my servers / laptop / phone. Was using Bitwarden for that a while back but decided I’d rather self host and run my own backups, with blackjack and hookers.
Great for hosting roms on my server and pulling over to whatever device needs them.