Brew my own usb microphone

Take one tiny2040 and one electret microphone and make my own usb microphone!

Of course it’s not easy! So far I can’t even get started as I can’t get libusb to play with the plug&play system on this desktop. Step 1 seems to be to understand the PnP protocol used by PulseAudio…

… or is it? Any pointers anyone?