The solution: HOWTO install Debian 10 (buster) on your non-rooted Android smartphone
What is it?
a shell script to install Debian 10 (buster) via debootstrap in a Termux environment
supported Debian versions also include: Debian testing (bullseye), Debian unstable (sid)
supported architectures include: armel, armhf, arm64, i386, amd64
no root permissions ...
Even though Google states that this works for the Android 9 and 10 images as well from my experience it works only for the Android 11 preview images.
I have tested this on Windows using the latest default x86 Google enabled images shown in the emulator manager for Android 10 and 11. As test app I used an Telegram armv7 only apk file from 2019:
Android-R - (...