Hi @Julien,
thanks for the answer. I actually reached out to support but did not get an answer. I found another post with the 2.4 board where @dandangerous posted a description. Hope that @Norway can confirm the pinout.
Goal is the following circuit that includes a run switch
and a selector to switch between a PWM speed control signal and the speed pot like shown here
What a journey… hopefully I can report success without blowing up my board