How to create group video conferences?

Question

Video broadcast

Is there a video service that can provide something like this functionality. Or what are the implementation options?

There is a host and several conference rooms. Conference participants can communicate via video only among themselves, while they see the main broadcast from the host, and their colleagues in a small window.
The bottom line is that the presenter can simultaneously broadcast to several rooms. It would also be a good mechanism when 1 conference participant could raise his hand and the host could turn on his microphone so that all participants from all conferences could hear.

Attached the diagram. Thank you!

P.S. The conference is all online.

Answer 1

zoom

Answer 2

In my opinion there is no such thing. Because usually the rooms are isolated...