I finally got to the point where I can build, error-free, a Python Kivy APK with Buildozer 1.0.
I build 2 sample apps, one with basic Python code, another with additional Python package (paho-mqtt).
I can install the APK with mqtt but when run, it closes immediatelly. 
The basic Python app will not even install.
The smartphone is a Nokia 6.1 with Android 10.
As said I am using buildozer 1.0, Python 3.8.2, openjdk 1.8.0_252, Android NDK r19c running on Ubuntu 20.04 Desktop 64bit (in VirtualBox 6.1).
Are compatibility issues among above? Can it be solved? How?
NB: As my smartphone is not recognised by Buildozer when hooked up with USB to VM, I download the APK using 'buildozer' serve and the Chrome browser on my smartphone.
Have you tried running it on android 9?
I also have similar issue where app working on 9 but failing on android 10.
Python Kivy-Buildozer APK not installing - running on Android 10?