Android may be technically 'open source' but it is not a collaborative project. It is completely controlled by Google, who are reducing the frequency of their source code releases and gradually making it more difficult for third-party Android forks to survive by convincing app vendors to make their apps refuse work on non-'certified' Google Android installations.

Alternative phone operating systems are the way to go if you really want to de-Google. Lots of them can run Android apps as well as the Android forks for now, and their own app libraries are growing rapidly as developers get tired of Google's shenanigans.