Our ISV team is in the process of approving the applications to use the new SDK. Thanks for your feedback about the confirmation email, I will pass this along to our team.
As for your question about the video streams, it only pushes one stream at a time, so user A can see you, and you can see user B. Also the Fully Customizable SDK cannot be accessed via the Zoom App, instead, it is a video as a service product. You can read more about it here:
“Sessions are not Zoom Meetings; instead, with no default user-interface, this SDK is designed to support unique video applications.”