Binaural Recording, super simple setup with lav mics and android phone

I want to do binaural recordings.

In theory recording is not that complicated, mic parts are really cheap and especially emulating ears can be done with really small mics.

But mics are also kind of obscure, and as always, the supply targets big studios or hobbyists.

• most recorders that do stereo only allow XLR inputs, which are huge and chunky, not that suited for carrying
• most mics are XLR
• most aux ports assume mono mic input
• Android recording software sucks pretty much, even getting lossless but compressed FLAC is not a thing

my attempts

I bought the following components

• RØDE SmartLav+ : 2 identical lav mics that don't seem to filter out ambient noise. Others like the "Lavalier Go" seem to do that
• RØDE AI Micro: a small audio interface that apparently supports 2 mic inputs, should supply them as 2 separate channels (I mean, obviously, right?) and has a monitor Aux port
• Android smartphone with "RecordEqualizer" or "RecStudio" (both support stereo output, choosing the source, WAV format)

After a first test, the audio is not separated into channels by left and right mic. Either the audio interface needs to be changed (needs an app??) or it is actually that limited that both mics are mixed into a single stereo stream, making it useless for this application.

Update:

• I tried the proprietary RØDE Reporter app, the system asked me to allow usb access to the app, which prompted me for a firmware upgrade
• the upgrade ran even without network permission, is the firmware inside the apk??
• nothing has changed. Also tried com.github.ryonakano.reco on Linux (which is pretty nice and supports FLAC), same mixed stereo channels

Alternatives

There is always the option to build an own device, or switch to XLR, or find a recording device that can record lossless (I dont trust these devices and want to do the encoding myself).

All the rest like an artificial head etc are peripheral, as I am already struggling with the fundamental issues.