Can you use the wacom digitizer (with a PC) while in monitor mode?
If, you mean, “Can I connect the Max2 to a PC and use the touchscreen functionality of the Max2 on the PC”…then yes you can using the HDMI for screen and the USB with ADB for touchscreen functionality.
Example set up
https://www.mobileread.com/forums/showpost.php?p=3685610&postcount=522
The set-up indicated by everalm will allow for a few mouse controls translated from touchscreen events, but not for example the pressure values that are associated with a wacom.
It could be done… It’s not there yet.
I think Onyx should streamline the idea and implement the integration of touchscreen/wacom with HDMI monitor, probably as a HID (Human Interface Device) through the USB connection. Flexibility should be maintained though: today I was editing some files on the portable desktop, using the Max2 as both a monitor and touchpad, then I just uploaded the files on that same Max2 while simultaneously using it as a monitor… So, maybe there could be a switch “USB HID / ADB+MTP”.