I don’t think the nozzle would have to be open source for this to be useful, just a printer that can be modified to print on things other than paper and be cool about whatever cartridges you put it it would be great. Inkjet cartridges are a little messy, but easy to refill at home, whit the printers DRM like check’s being the main issue.
This project reverse engineered cartridge control and developed an ESP32 controlled hand held printer:
http://spritesmods.com/?art=magicbrush&page=3