SDK for Nikon J series cameras

Could anyone help me to find the SDK for Nikon J series cameras?
Thank you.

Have you looked into gphoto2?

No, I did not. But I tried Digicam Control. The only draw back is it takes about 3 seconds to write the frame to the computer hard disk. Is the gphoto faster in writing the file?.

Could you write to a SSD? Then send the photo to your slower drive? I don’t know I’m just throwing that out there.
Rob Teed