that is often true by default, but AGC can be disabled, and i’d think a good recording app would do so.
for example on iOS the magic trick is currently to configure AVAudioSession with AVAudioSessionModeMeasurement (docs)
if one happens to be compiling a DSP graph from Faust, use the -NOAGC flag.
haven’t looked at android audio in a few years so can’t speak to it.
sorry for the technical derailment.
i too am interested in a good mobile recording setup, in my case for iphone/ipod (and not actually for personal use, but for a client.) specifically it would be awesome to find a way to power and capture some decent binaural microphones like roland CS-10EM… dunno if this is really feasible