APK is outdated.
Google play store has removed the ability to upload APK's but even if they didn't we still need a way to put it into android studio and make a keystore to release it.
I don't claim to know what process happens to convert the app on microStudio but if we can make an AAB (Android app bundle) file instead of an APK then this would allow people to actually release there creations from microStudio to the google play store. But like I said, not sure if the build process is something you have control over or if it is third party?