Earlier quoted context omitted.
One reason to repurpose desktops is that you get a full ATX Motherboard with SATA ports! If you are doing a DIY NAS with HDDs then you want real SATA ports. Or a well supported PCI card with SATA Ports, which you cant sensibly connect to a Laptop or micro PC. Sure, you might be able to use Thunderbolt to reliably hook up an external PCI chassis, but then you might as well buy a NAS at that point or use a full tower c…
You can definitely get PCIe on some micro PCs. I have a Lenovo m920q that I use with a Mellanox NIC as my router. You could certainly install a SAS or SATA controller, the issue would be having somewhere to mount the drives, and a way to power them. External SAS enclosures are not cheap.
Sadly this is what I discovered.
I'd hoped there would be cheap external drive bays to mount HDDs in and connect to the mini PC over SATA.
But alas there isnt really.
It makes more sense to just use a PC Case and mount the drives that way.