An exciting milestone in the project was achieved right before New Year's Eve: the design is finished for the first PCB revision, time to order the boards.
We ordered bare boards (no assembly) and STM stencil from JLCPCB in China. We will solder a couple of initial prototypes ourselves, and it is going to be fun. I expect that CM4 connectors may be challenging for manual soldering. We will see.
A spoiler for the next update. PCBs are already on their way from China.