Android basically ran a long bait and switch game. It came out as open source, achieved wide adoption, important online services like banking and government-related moved to it.
In "Androids: The Team That Built the Android Operating System" by Chet Haase (a book you shouldn't waste time on), it is very clear that making Android open source (i.e. AOSP) was almost by accident. Google was pretty confident that Android could be just as successful if it were a more closed ecosystem.
And it seems to be that Google is increasingly regretting that decision and closing things down bit by bit, from Play store policy, all the Play services BS, to how they ship security patches, and now all the developer verification. Google discovers that it's easier to make money if they just control everything.
Folks around here that repeatedly mix Android with Linux, should also be happy that for whatever internal political reasons, they ended up not rebooting it with Fuchsia, or simply replacing the Linux kernel with Zircon.
As everything else, especially anything with a GPL license, has been removed already, with exception of the Linux kernel.
It's a kernel per se, and any OS built on it is considered a Linux OS. "The Linux kernel is the core of any Linux operating system." - kernel readme
Linux.com refers to the kernel itself as an OS though, I think to relate to people who have only heard of OSes like Windows. And calls Android a platform based on the Linux OS :S
Pity that Android doesn't run any Linux userspace application, unless one makes use of workarounds, like termux having to fit within the constrains of Android sandbox and NDK limitations.
Well they've contributed upstream to Linux kinda as a result, so that's nice, but Android being Linux is no reason for me to want to use it. Like, so is the Amazon Firestick.
Now they are locking it all down.