Unpopular take: Android experience isn’t as open source as they claim for most android users.
Manufacturers can opt for closed source implementations of Android.
Android core development is not community driven.
Manufacturers of android phones can (and will) void your warranty if you tinker with the OS. (Same as Apple)
It is apparently much easier to tinker with Android than iOS, Sailfish and Ubuntu touch use android code.
The real hero is Linux.
Is Android open source? Yes, it is. But most implementations are not.