Do current smart phones support this?
I can't imagine Apple being too keen on allowing this sort of thing. No idea about Android
(Thankfully MacBooks do at least physically disconnect the microphones if you close the lid.)
And of course it doesn't have to be on the display, given they already have a cutout island in the display where they could place such a thing.
What is the mechanism for this? It seems like this would be a software system.