Oh, I totally forgot to add my OS, I wonder how you could divine that 
I just now updated it to macOS Big Sur 11.6, after deinstalling the old tablet driver and removing the accessibility list entries. I then got the according XP-Pen driver (XP-PENMac_3.2.2_211029(New UI Driver)) for Big Sur.
"PenTablet.app" and "PenTablet_Driver.app" are added to the list for „Accessibility“ and „Input Monitoring“.
So the setup should be correct. Everything is still working fine in the tool "artrage Lite".
In GIMP I still see the following input devices (no changes to yesterday):
Core Pointer
Quartz Cursor
Quartz Eraser
Quartz Pen
I guess the Quartz Pen is the XP-Pen. Still no pressure functionality, as you said: basically working as a mouse. That’s why I thought this would be a GIMP issue. Also, with the new driver there is now a lag when drawing a line (again, only in GIMP).
I basically have the same settings as you on your Linux machine. I set the Quartz Pen to „Screen“ and played around with the pressure curve and the dynamic mode.
You’re right, in hindsight a Wacom would probably have been the better choice. When buying something for the first time, it’s always difficult to choose the selection criteria, I didn’t think too much about SW compatibility. I just wanted something simple to try out before making a bigger investment. Next time I’ll be wiser
Anyway, thanks a lot for your input so far!
I just now updated it to macOS Big Sur 11.6, after deinstalling the old tablet driver and removing the accessibility list entries. I then got the according XP-Pen driver (XP-PENMac_3.2.2_211029(New UI Driver)) for Big Sur.
"PenTablet.app" and "PenTablet_Driver.app" are added to the list for „Accessibility“ and „Input Monitoring“.
So the setup should be correct. Everything is still working fine in the tool "artrage Lite".
In GIMP I still see the following input devices (no changes to yesterday):
Core Pointer
Quartz Cursor
Quartz Eraser
Quartz Pen
I guess the Quartz Pen is the XP-Pen. Still no pressure functionality, as you said: basically working as a mouse. That’s why I thought this would be a GIMP issue. Also, with the new driver there is now a lag when drawing a line (again, only in GIMP).
I basically have the same settings as you on your Linux machine. I set the Quartz Pen to „Screen“ and played around with the pressure curve and the dynamic mode.
You’re right, in hindsight a Wacom would probably have been the better choice. When buying something for the first time, it’s always difficult to choose the selection criteria, I didn’t think too much about SW compatibility. I just wanted something simple to try out before making a bigger investment. Next time I’ll be wiser
Anyway, thanks a lot for your input so far!