We opened the mold finally. And outsourced the PCB to a studio. That was not a minor effort. They added an USB type C charger that is really fancy (and also almost drove me crazy because of EMI)
I also had some trouble tuning up the PID constants. The motors we got from the supplier were just too different from the ones we originally designed Plobot with. But, oh, well... it works!
It's fair to share that there is an amazing article that helped me to understand the coding structure that was used to implement the PID inside of the turning of Plobot. Here is a detailed PDF explaining it.
And the PID library itself, we used this open source approach that works surprisingly well.