Feature Suggestion - Doorbell for Breakout Rooms

It would be so, so helpful if the host of a meeting was able to alert the participants in a specific breakout room that they're coming in before entering the room, and without messaging all the other rooms at the same time. Even just a setting you could turn on that would sound a "doorbell" whenever someone enters a breakout room would be great.

Even better would be if the host could send messages to individual participants (and have the participants message the host) when the host isn't in the same room.

The use case: I'm a mediator. The breakout rooms often have confidential, emotionally-weighty conversations. The participants are aware that I might pop in at some point, but it's awkward to interrupt them mid-sentence, especially if they haven't noticed that I've arrived. I also don't necessarily want everyone in all the breakout rooms to know when I'm entering or leaving each room, so sending an announcement to all rooms doesn't work.