This is exactly what I did when the 12th gen came out. My original mainboard is now running our home NAS and NVR.
[0] https://frame.work/products/cooler-master-mainboard-case [1] https://github.com/FrameworkComputer/Mainboard
I also looked at TB4 disk enclosures, but the bandwidth was overkill for spinning rust hard disks. There's a lot you can do with 4 USB-C/TB4 ports. I also have a Coral USB stick connected for frigate.video inference and a 2.5Gbps USB NIC (waiting for better thunderbolt 10Gbps NICs to become available). One fun convergence is when I want a keyboard / display / mouse I can plug the mainboard server into the same thunderbolt dock I use for my laptop peripherals.
[1] https://sabrent.com/products/ds-sc5b
[2] https://github.com/FrameworkComputer/Mainboard/tree/main/Mec...