Now I can actually see where I’ve drawn!
Try googling for: “XServer XSDL”
After a bit of tinkering, my device appeared also as a pointer as “Network Tablet Pen (0)” . Using it
xinput map-to-output “$( xinput list --id-only “Network Tablet Pen (0)” )” HDMI-0
worked like a charm
Try the changes to the code I made in pull request 95.