Simple demonstration of how to build an app using Andoid's alarm manager and service implemented in Kivy
Inside your project locate PythonActivity.java it should be inside
.buildozer/android/platform/python-for-android/pythonforandroid/bootstraps/sdl2/build/src/main/java/org/kivy/android/PythonActivity.java
and replace it with one from java_scr folder, then add KivyAlarmReceiver.java to the same folder where PythonActivity.java is, then replace AndroidManifest.tmpl.xml
it should be inside .buildozer/android/platform/python-for-android/pythonforandroid/bootstraps/sdl2/build/templates/AndroidManifest.tmpl.xml
with the one from java_scr folder
then check buildozer.spec file or simply copy it.
If you've alredy built some app before you should buildozer android clean
before building your app again with this changes.
Already built app is in the bin folder.