@lulu-gh USB devices are supported in VoodooI2C as long as they support he PTP protocol. That project has long since been deprecated and will not be supported. Please do not ask us to support it.
@shiecldk We don't take donations, we work on a volunteer/on-our-free time basis and do not take donations (nor are there any plans to do so). As previously mentioned dual screens is not tested as the hardware very exotic. It's very hard to test/debug something when you don't have the actual hardware on hand. Another problem is macOS does not natively support touchscreens and we are emulating a virtual finger for the stylus.
I also found if I delete the IOKitPersonalities for these items in VoodooI2CHID.kext's plist:
VoodooI2CHIDDevice Multitouch HID Event Driver
VoodooI2CHIDDevice Stylus HID Event Driver
VoodooI2CHIDDevice Touchscreen HID Event Driver
The TPL0 (secondary screen) would be unusable, but TPL1 (main screen) still works as trackpad. Some device detection/assign is playing a part in the TPL0, even after I remove TPL1 from the motherboard, which doesn't make sense as the only differences are the connector type (DP in TPL0 vs eDP in TPL1), resolution (3840 x 1100 vs 3840 x 2160), and HID (ELAN9008 vs ELAN9009). Tried renaming ELAN9008 to ELAN9009, which still have the same effect.
@shiecldk IOKitPersonalities usually for telling the OS to load the driver for a particular device.
I keep mentioning that the stylus code was hacked together AND your combination of multi-screen devices is exotic. Technically speaking, VoodooI2C should work across numerous devices BUT multi-screen devices are not found in real Apple hardware AND macOS does not natively support styluses. That is why I am saying it's hacked together.
You are pretty much in unexplored waters here and while I can try to explain what's going on, it's quite tough as I have not written that code (@alexandred ha) nor I have not looked at that particular code in well over 2 years. You may be better off creating a separate satellite and directly interfacing with VoodooInput.