I run desktop linux via postmarketOS on a Lenovo Duet 5 (Snapdragon 7c). It isn't the most powerful device and the webcam doesn't work but other than that it works well and battery life is excellent
I recently installed PostmarketOS and ran into the audio issue as well.
It is resolved by editing the rt5682-max98357a/HiFi.conf file to change the playback channels from 2 to 4. There is extra bit to clean up, but that is the simple fix.
IIRC, it's because the ARM designs tend to use camera modules that come from smartphone-land.
Cameras used on x86-64 usually just work using that usb webcam standard driver (what is that called again? uvcvideo?).
But these smartphone-land cameras don't adhere to that standard, they probably don't connect using USB. They are designed to be used with the SoC vendor's downstream fork of Android or whatever, using proprietary blobs.
A similar thing is happening in Intel land recently, where the cameras use ipu6 / ipu7 chips rather than dumping simple frames over USB. But this way we get a higher resolution / quality at least.
It’s usually MIPI or some variant. There’s probably a way to enable the video stream but you also have to talk to the control module itself which is on a different bus.
The documentation says audio doesnt work as well. did you find a way to solve it or it came solved when you installed ?