Android, since version 10, has been supporting Modular System Components. This allows to expedite functional and security updates to the Android ecosystem outside of major API level releases and make new functionality backward compatible on already-released Android versions. End-user devices can receive updates to these modularized system components from the Google Play Store infrastructure or through a partner-provided over-the-air (OTA) mechanism.
With Android Extension SDKs, it is possible to extend the support of certain platform functionality to existing Android versions, increasing user reach.
For example, the PhotoPicker APIs previously available only on API level 33 (Android T) and above are now also available all the way back to API level 30 (Android R) through the Extension SDK on devices with an R extension version of at least 2.
The API reference pages for SDK Extension APIs specify the earliest SDK extension version that your app can use to access an API. If the documentation also specifies an Android platform version (referenced by API level), then that API is also available for all devices running that version of Android or higher.