I2S Audio send and receive, Sensor data, Custom controller

Hi! new here with this amazing openHD!

I’m currently listing parts to be use on a ground RC robot. I can code in c/c++ and python.

Is I2S Audio supported or is there a way to make it work? Cause my current assumptions now is that it should work, just needs to be the default audio in and out so I can send and receive audio. This particular product is on my list https://learn.adafruit.com/adafruit-voice-bonnet/overview

Based on the wiki, audio from air should be easy to setup. But Audio from gnd to air, I only found this comment on a website. https://gitmemory.com/issue/HD-Fpv/Open.HD/120/517840137 . I can only try after I purchased the parts.

2nd one is I have sensor reading from RPI-AIR, how can I send it to the RPI-GS? Is there any channel or stream of data that I can add it as part of the message being sent.

3rd is my robot may need custom code for stabilization (not supported by ordinary APM rover setup). So to use the RC control I need to conform with the MAVlink commands and telemetry data, am I right?