Starting in August, Google will require new apps submitted to the Play Store to be in Android App Bundle (AAB) format instead of the APKs used so far. Amazon will not be outdone, the company has announced that it is working on AAB support for its Appstore (which will also be the default source of Android apps on Windows 11).
The Amazon Appstore will continue to accept APK submissions from developers, in fact, the submission process will not change. Bundles have several advantages over APKs, as they allow smaller app downloads and allow dynamic features such as on-demand upload.
Size reduction is one of the biggest benefits of Android app sets (more information here)
However, not all the features of the bundles will be available at launch, Amazon says that some features will be activated gradually over time. More details will be available once android app bundle support in the Amazon Appstore closes to launch.