Double click on the Trinket M0 reset. When the TRINKETBOOT USB drive appears, drag and drop the file KBDADVUARTUSBH.ino.trinket_m0.uf2 on the the drive. This programs to the Trinket M0 to act as a USB ...
This programs to the Trinket M0 to act as a USB host for the mouse. USB mouse HID reports are send out the UART TX (4) pin. The source code is at https://github.com ...