yGuard can be used to obfuscate code that will result in an APK. In order to this one needs to:

• disable R8 obfuscation and shrinking
• use yGuard as an extra step in the build file
• run D8 after yGuard

This has the benefit that yGuard is very extensible and well documented in comparison to R8.
Potentially this should be accompanied with a small Hello World app and Android Studio Project file.

Useful information can be found in the Google documentation.