Here is the breakdown of the ABPop apk assets.
When the extraction is complete, one common folder in every game is the assets. This apk uses the old method to make the game work by playing the sound directly into the game. However, due to some complaints, the developers have decided to place into some file and zip it with other extension that no software could open up. Not easy.
Focus on the assets here.
The images, audio and font can be played around. Plus, you can make install the fonts in the folder and use it as you wish anywhere.