Choosing camera in Messenger App

I can't select which camera gets used in Messenger, the Macbook built-in or a Logi webcam I've added on. All the websites I've looked at say go to Apple>System Settings>Privacy & Security>Camera and "allow the applications below to access your camera". This isn't helpful, it just allows the built-in camera to operate in Messenger. I see that WhatsApp offers a camera selection item in the menu (Call>Camera>select from a list of installed cameras). I need a way to select which camera I want to use in Messenger, the built-in camera or my webcam. Anyone know of a way to do this?