So we know the annoying problem with the Sony Nex Series and External Microphone.
Of course there are microphones for this from Sony but they are only plugged in and B are very expensive.

Yes, one had the idea that one could use the Sony smart accessory port.
Unfortunately, I only found attempts but no successful ones because you couldn't find the right resistors to tell the device "hey, I'm a micro".
All the discussions about it ended in about 2011/2012.
There was a version that required disassembling one of those expensive mics, but that's a bit pricey.

Until I found this video by accident .
https://youtu.be/fL7hPrfTijg
Thx for the Creator and that i can Publish it!

Unfortunately, the users all text is in Kyrlian and unreadable for me without a translator.
But about 19 minutes of the video are subtitled in English.
There is also a file attached for his circuit board which I cannot open.