Just yesterday I was brainstorming with ChatGPT about this. I have an ancient QNAP plus a slightly less ancient NUC running PiHole, Wireguard and other services. Both need replaced, so why not combine them?
I don't know much about ZFS, but it sounds like I need to learn. Docker may have conquered the world, but I plan to stay with LXD for services.
The one thing I take issue with: an appliance like this runs 24/7. It should be low power and fanless. A processor like the N100 seems like the obvious choice.
It also surprised me that the author said "4 Cores, Xeon Server CPU can be had for cheap".
But the specs also said ECC RAM and I don't think the N100 supports that.