Just like in the real world, when you meet in an office lobby, you are still able to communicate with others openly, even if the meeting is yet to start. Bring the meeting chat into the Lobby as well so participants can start the conversation before the meeting starts. For example, meeting owner is running late, they jump over to the meeting and leave a message in chat letting everyone know the meeting will start in 2 minutes. Another example, participants start to discuss the agenda before the call start, bringing up new topics they want to cover.
