I see that Sensors Mezzanine board's low-speed interface connector is a stackable 2-row by 20-pin through-hole connector with 2mm pin pitch. "Stackable" meaning it's basically a female (receptacle) header that can accept a board on top, and has long pins that can plug into the baseboard.
Does anyone know of a source for these? I've searched at all the obvious US suppliers using all criteria I can think of. Plenty of such connectors for 0.1-inch pitch, and plenty of 2mm connectors of all genders and configurations except long pins for stacking. They must exist, but where?!