The Android 12 sources have been pushed out to AOSP in officially releasing this newest version of Android. Android 12 features a new user-interface with redesigned widgets and other graphical enhancements, more efficient system performance, more responsive notifications, faster machine learning performance, various privacy enhancements, AVIF image support, a variety of new developer APIs, and many other enhancements throughout the mobile stack.
More details on the Android 12 release and the AOSP availability via the Android Developers' blog .