I found this page form ST. It seems as they support their own PDM microphones with their lower ST embedded systems.
MP34DT01is a MEMS digital out audio sensor .
PDM is a 3 Mbit/sec serial bus for audio.
So I think it might be possible to support them om Micropython too.
I know that there is already a microphone board, and it is uses the ADC to import audio.
This Mems micropones need no additional amplifier, and they are small and robust.
So they might be integrated on board of a new pyboard version.
Just my 0.02c