I tried to get running the audio board-MIC+ in Aetina AN810 carrier board with a Jetson Xavier NX. My first try was with,
$ sudo /opt/nvidia/jetson-io/jetson-io.py
However, it seems that for AN810 carrier board doesn’t work. In the documentations of Aetina AN810 Carrier board, I found that the I2S port available is I2S1 and not I2S5(like in dev kit).

So, I looked into how to activate the I2S 1, but to be honest I got confused. I am not sure what parts of the kernel must be modified (dts or pinmux).
Links:
P.D.
The audio board has basically a codec (NXP1334A) and a I2S MEMS microphone(SPH0645), both of them I2S devices.