Wish me luck! I haven't tested the actual #USBpassthrough setup yet - the person I am helping is geographically distant, so I have to find a good time to do this via #rustdesk on their machine.

A dry-run on my own machine lets me access the docker cups server admin interface on localhost, and I can see all /dev files in /dev on the docker container (not secure, but convenient for the remote user, and this docker instance is not exposed on the network)