Now, this most likelly mean *FULLY* working. I now can get audio/video and have confirmarion from someone else that the arm, gripper and the distance sensors also work when connected to the S1 with this hack.
This is mostly to say that, yes: If DJI wanted to have the SDK on the S1, or make an EP expansion kit for the S1, they could.
I am now working on a Go library for SDK support. It is incomplete but it is already possible to see that at least doing object tracking with the API is fast enough. If anyone is interested on helping: