We don’t currently support digitizers via the InputDevice API, but I just added some rudimentary support that seems to work for my Wacom Intuos. Give it a try:
https://buildbot.panda3d.org/downloads/b67c7dd84f6174f439ccafc3339cd2e850e47930/
It adds the InputDevice.DeviceClass.digitizer class and the InputDevice.Axis.pressure axis. They should show up in device_tester.py.
Mine has only pressure, and not anything fancy like tilt or twist, so I did not add those as I couldn’t test them. They could be added fairly easily if I had some help figuring out the inputs, though.