I finally purchased a couple of PocketBeagles, I knew they would be small, but it is still amazing to see it close-up!
It is very thin too, it measured 4.60mm (the highest point is the surface of the Octavo module).
For connections, I purchased because these are cheaper than 2x18way. A total of four of these are needed to fully connect to the PocketBeagle, although that might not be necessary for all projects. Note that the header pins are connected to the underside of the PocketBeagle, not to the top side like the larger BeagleBone Black. The pins won't fit on the top side, because the Octavo module hits the plastic surround of the header pins. It seems to make sense, that the PocketBeagle would be plugged on top of a larger board.
The very helpful silkscreen shows the pin descriptions on the underside:
Here are some graphics of the top and bottom side, perhaps useful for documenting projects:
Renders of the PCB: