Virtual Microphone as default on Android

As an example: there are Bluetooth or USB microphones that can be added to the android. When you add them, they add also the 2nd microphone device to the android system - and they tell that this new device is the default audio input - while they are plugged. There is a driver that tells to the OS of android: “Now I am your microphone “ So, if this driver can tell to OS that “now I am your microphone, use me while I am plugged”, can there be an app that will do the same thing (from the software point of view) as these external microphones? Except that we do not have the real Bluetooth/USB microphone. Instead streaming the audio over Bluetooth/USB - we take it from a file. Additional information: It is possible to have audio input from microphone It is possible to have audio input from jack It is possible to have the audio input from Bluetooth It is possible also to have audio from USB  Is it possible to add another audio input - or use one of these audio inputs and feed the sound from a file ?