The problem with RPi is that you would be doing SATA over USB 3.0. It will work, but it's not great. Other SoC typically have just one native SATA link (like A

The problem with RPi is that you would be doing SATA over USB 3.0. It will work, but it's not great. Other SoC typically have just one native SATA link (like A20). SoCs with better connectivity exist - that's what ends up in consumer NAS products after all - but SBCs are sparse and expensive (e.g. MachiattoBIN). You could go for a CM module and do your own expansion board with a SATA controller on PCIe but then you may run up against the x1 bandwidth (if it's PCIe 2.0 then probably fine for two drives). ROCKPro64 has a x4 PCIe slot you could use with an HBA card I guess. But at this point I'd probably go for a Celeron ITX board. Some time ago I would suggest just getting a second-hand NAS and running Debian on it (like QNAP TS-219P) but with Debian 11 dropping support it is less appealing.