Thank you for the links, that morefine one seems really nice, would need to get 2.5Gb networking gear...
I currently have a single 16 core/64 GB ECC Ryzen tower with ZFS that I'd like to break into a ZFS ARM ECC NFS server with a separate small form factor Ryzen or ARM compute cluster.
https://morefine.com/products/morefine-s500-mini-pc
The FAQ question reads a bit funny:
"Q19:Support ECC RAM?
YES. S500+ Support ECC RAM,
But compatibility requirements are higher, and cannot be used casually."
Also, these AsRock products:
https://www.asrockind.com/en-gb/4X4%20BOX-V1000M
https://www.asrockind.com/en-gb/4X4%20BOX-R1000M