Don't know about the general case, but I can answer for one.
Using these two nice pictures of a Nanoracks deploy:
I was able to match the Japanese robot arm position in the NASA visualization tool DOUG
and then we can rotate the view to see the big picture of which way it's pointing.
So, diagonally nadir & aft.
See https://eoportal.org/web/eoportal/satellite-missions/content/-/article/pixl-1 for more details on the mission
Launched beginning of 2021!
Launch: PIXL-1, a 3U CubeSat mission of DLR, was launched as one of many payloads (total of 143 satellites) on the Transporter-1 mission of SpaceX from the Cape Canaveral Space Force Station (SLC-40) in Florida on 24 ...