I've put my device into USB bootloader mode and I've previously installed libusb-win32 drivers via Zadig. When I try to upload the firmware I get >python -m ch55xtool -f .pio\build\ch559\firmware.bin ...

Most regression tests are limited to the software level. For most of the continuous integration setup for the Arduino projects, as far as I know. They only compile the sketches in a virtual machine ...