enable proactive messaging for chat box into groupChats for meeting participants
There are numerous use cases for bots to send proactive messages to single individuals, teams-channels or groupChats, e.g. to all participants of a current meeting. There are workarounds to implement the personal proactive messaging, but they cannot be applied to groupChats for meeting participants, since the workaround relys on the fact, that the bot receives a conversation update once to be able to post a message to that user. Since meeting chats / groupChats only begin to exist once a person posts a message to it, there is no chance for the bot to create this conversation.
I recommend to implement a graph endpoint to create such a group chat or post a message to a meeting chat.