Sorry I missed the meeting. I hope all went well.
I've been working to use a raspberry pi with a touchscreen as a chording keyset keyboard. The demo works. I thought of using usb-otg to connect them but my pi doesn't support it. The last piece will instead connect over the network via usb-ip built into the linux kernel via the PythonUSBIP library.
A wrinkle that changed for me is that the debian and ubuntu usbip packages used to work but now are too old. The source is in the linux kernel but by default they aren't compiled. So that's a manual step each time the kernel version changes.
I plan to 3d print a stand at a good angle for using the pi touchscreen in this way.
If interested in any of this please let me know.