Hello Enrico,
I just opened the Mate 20 Pro and what i can say is this:[br]
There are two microphones at the bottom end of the phone. I can’t tell when which one is in use but both of them sit ''on top of'' small daughterboards. So the gasket for water- and dust proof isn,t placed at the end of the small holes but on top of it. The rear end of both holes should be plastic of the mid frame. In my opinion I don’t think it’s possible to break one of the gaskets by entering a pin in one of the holes but i can’t give you a guarantee for that.