Starting in August, Google will require new apps submitted to the Play Store to come in the Android App Bundle (AAB) format instead of the APKs that were used until now. Amazon is not going to be left behind, the company 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 make for smaller app downloads and enable dynamic features such as on-demand loading.
Size reduction is one of the biggest advantages of Android App Bundles (more info here)
However, not all features of bundles will be available at launch, Amazon says that some features will be enabled incrementally over time. More details will be available once Android App Bundle support in the Amazon Appstore gets closer to launch.