Fun journey! It would be fascinating to see what's inside the dongle. I wonder if it's programmable or just a simple circuit.

Yes, a neat follow-up would be to clone the copy protection device with a cheap microcontroller. A lot of these devices were filled with epoxy, but it would be funny to find out these were all just 1Kbit EEPROMs. Such an article could give some background on parallel port communication, EEPROMs, and how regular printer data was passed through.