So, based on the testing shown in this post in another thread:
The microphone input doesn’t work for Raspberry Pi’s on the audio interface on the main board. This is a pretty big bug as that audio working was one of the core pieces of hardware I was looking for in a portable.
Are there any plans to fix it, or is it just a no-go for RPI things?
FWIW I’ve switched to a USB jack adapter and it’s working great. I don’t have any hopes that input will ever work. However I am considering repurposing the jack as a GPIO port.