“Low-power” would probably help as well.
A mini-ITX Supermicro X10SDV (Xeon D-1500, 6 SATA) looks like the perfect candidate. It is old, and best snapped second hand if you can, but still sold new. @Davvo should, at some point, give us feed back on a Datto/Gigabyte equivalent.
Alternatively A2SDi boards (Atom C3000, 8-12 SATA). Expensive new—and hard to find used.
Cheap alternative, if you only require 1 GbE and have access to a 3D printer: Gigabyte MJ11-EC1 (embedded EPYC, 8 SATA). Not new, but available for cheap from Germany.
Do you want to run apps/VMs on top of storage?