Diskomater appears to be an open source, platform agnostic version of this underlying technology!

In case, like me, "Target Disk Mode" is not something you're familiar with:

> People also ask What is the target disk mode? If you have two Mac computers with USB, USB-C or Thunderbolt ports, you can connect them so that one of them appears as an external hard disk on the other. This is called target disk mode. Note: If either of the computers has macOS 11 or later installed, you must connect the two computers using a Thunderbolt cable.

Sidenote: Thunderbolt cables are special USB-C cables, i.e. the wire between your Mac and the USB-C power brick.