Hey! Glad my project inspired you! If you want more pins on the WS touch module, you can use an i2c expander board. It uses only two wires for SDA and SCL (plus two for power) and gives you a bunch of digital pins. And there is one i2c port available on the board (I’m using it to connect an IMU in my other project.
For mounting the board I clamped it between a ring and some tabs holding the module down (I’ll link to photos soon)
I also looked into QMK integration and it seems it would be doable, but would require some extra coding to make the touch interface talk to QMK. Then you would still need custom firmware to animate the screen.
Also for the screen, I recommend looking into LVGL. It’s a library that allows you to build reactive interfaces easily. It even had a UI builder app where you can drag and drop your elements to make your interface. It’s. Bit buggy but the best I found.
Lastly, my idea for my trackpad project right now is to actually use it separately from the keyboard entirely and have a usb splitter hidden in the case to connect both.