I'm a little proud of this. It took ages to get it to work, but I was given a 2009 Mac Mini to try out, which was running Snep. I've got it running Catalina on a 250GB SSD I had laying around. If anyone wants to do this themselves, and has issues with the Catalina patch, even though the machine doesn't have USB 3, the install will fail if you use a USB 3 device. Something to do with how the host negotiates with the device, I think. But use a USB 2.0 flash drive if you have one, or I guess you could use a USB 3 external hard drive with a USB 2 cable. The only thing I had that worked, was an external USB-C SSD. I've got a few USB A to C cables that are wired in USB 2.0 mode. They came with an oscilloscope and logic analyzer that I recently bought.
Point being, use something that can run in USB 2.0 mode. But I'm pretty happy with how this has turned out. I'd love to throw some more RAM in it, but it's working well enough. It'll be perfect for my electronics hobby since I have slightly weird hardware like aforementioned scopes, EEPROM programmers, UART interfaces, etc, which like running under a *nix environment. So this thing will be perfect. It was a fun little project getting it working, and I'm happy.