So I’ve got a basic KMK Firmware working now, using the pin out of the v2 board above including an I/O expander. That required a lot of jumpers on my v1 board:
Firmware at: X1CarbonGen10/firmware at main · cscott/X1CarbonGen10 · GitHub
I’ll work on a qmk firmware next, which should allow trackpoint support. (And then from there probably a zmk firmware, which would require porting the ps/2 support from qmk – so I want to make sure the qmk configuration works first.)