HiByMusic will run on the AR M2 but, if I remember correctly as it has been a while, I had to use APK Editor Pro on the HyByMusic APK to allow it to install on the lower version of Android. I'm running HiByMusic V3.0.0 build 5481 which I downloaded from APKPure. Technically, I think it should not provide as good or better sound as it runs through the Android system whereas AR Music Player is supposed to bypass the android sound limitations. That said, I find with the great EQ and the Sound Field plugin offered by HiByMusic that it often sounds better. It's so much easier and intuitive to use as well.
I think this is what I followed with regard to editing the APK to allow installation on the lower version of Android that is on our AR M2:
I think this is what I followed with regard to editing the APK to allow installation on the lower version of Android that is on our AR M2: