I took a WaveShare RP2040-Touch-LCD-1.28and made a program to use it as a touchscreen. This is still very much in the beta phase but the proof of concept works. Here’s my GitHub repo for it.
I’m planning on integrating it into my next split near the thumb cluster.
You could pull the trackpad logic out of this but it would need some rewrite.
For the next version , I’m actually looking into implementing the drivers into QMK keyboard firmware as it has a whole trackpad management as well that does what I wrote and more and also is much more flexible.