AndroidX which was initially named as Android support library is now pushed publicly to AOSP( Android Open Source Project) for further development and fixing of bugs. Android developer community can now contribute to AndroidX.
In the beginning, it was just a small library for providing backward compatibility for Android platform APIs( means new Android platform APIs could use assets such as data and GUI of the previous version), therefore its development was bound with the platform. As a result, developers contribution for AndroidX were limited. Somehow, if developers wanted to contribute to the full development of AndroidX, then they had to check up over 40 GB of Android platform code. Obviously, it was very difficult for developers.
To solve this issue over 2 years ago, Google began separating the AndroidX library to its own separate build from Android platform builds using the process of unbundling. They also moved API tracking tools and documentation generation out of the Android platform build.
Now, AndroidX is not completely tied up with the Android Platform API, which would definitely help it to move a further step for easy and effective development.
Further, AndroidX gradually becomes a large library that includes Appcompat, Room and WorkManger for providing backward compatibility