https://github.com/guysoft/The-Arduino-SD-Game-Boy-Printer/tree/esp8266
emulates the gameboy printer https://github.com/Raphael-Boichot/GameboyPrinterPaperSimulation
This is the the first arduino mod, mainly for reference
https://github.com/davedarko/GBPrinter
Octavifs forked and updated this to have more features, I've tried this but the repo is so old that it doesn't work properly. Prints a single line and hangs, no software really available.
https://github.com/octavifs/GBPrinter