Awesome
USBPrinter driver for USB Host Library for SAMD
This driver is designed to work for small USB thermal printers. Do not expect this to work for laser or inkjet printers because they require complex software support.
This has been tested with the USB Host Library for SAMD and the ESC POS Printer library on an Arduino Zero.
https://github.com/gdsports/USB_Host_Library_SAMD
https://github.com/gdsports/ESC_POS_Printer
The ESC POS library send printer ESC/POS commands for different font sizes, graphics mode, etc. It is based on the Adafruit Thermal printer library but modified to work with USB thermal receipt printers. Note different thermal printers from even if from the same manufacturers implement different subsets of the ESC POS commands. You will have to find the ones that work on your printer.
Related
This driver does not work on the USB Host Shield but the following version does.
https://github.com/gdsports/USBPrinter_uhs2
The following driver works on Teensy 3.6 boards.