Is there a way to install AAB file via App Manager?

[MuntashirAkon]

AAB stands for Android App Bundle which is not an Android package (APK). This is essentially an intermediate format which stores data for all the supported platforms and APIs in a single file which can later be converted into an APK file or a set of split APKs via bundletool based on the requirements of the target device. This means that if you set specific configurations (platform type, language, display resolution, etc.) before you generate the APK(s), the tool will produce APK(s) only for those configurations. Since a typical device (phone, tablet, TV or watch) uses only a small subset of all the configurations available, the total size of the split APKs generated by the tool is much less than a universal APK (that is, a single APK file that has all the supported configurations). This format and tool are used by Google Play Store to generate split APKs for the target device to reduce the total size of the files so that it takes less time to deliver and install the app. This also allows Google Play Store to support a feature known as Dynamic Delivery (that is, an app can request the user to download split APKs based on requirements after installing the app).

Now, Android ensures the legitimacy of an app by a method called app signing. In this method, the APK(s) are digitally signed by the app developer before releasing them out in the wild, and Android can later verify whether the integrity of the files are preserved by running a verification test. So, when you generate APK(s) in your side, there is no way to get it signed by the original app developer (in Google Play Store, for example, a developer must upload their signing key along with the AAB file so that Google can sign the generated APK files for them). You can still sign the app yourself and use it for yourself, but this can be risky because you must have downloaded the AAB file from the Internet, and there's no easy way to figure out if the AAB file is modified by a malicious agent or adversary. So, while developing App Manager, it was concluded that AAB format is primarily meant to be used by the developers and the app stores and shouldn't be handled by App Manager. If a developer uploads only the AAB files in their release page, you should ask them to publish APK or APKS files instead.