Only devs that don't code for Android can ever consider it an open source Linux based OS.
The fact that it uses Linux kernel and related features is an implementation detail, only visible to Google and OEMs.
What regular developers see is a Java/Kotlin based userland, with a native layer having a set of predefined stable APIs, which includes ISO C, ISO C++ standard libraries, a POSIX subset, GL/Vulkan and a couple of Android specific ones.
Tomorrow Android can be another Fucshia subsystem, and again, only Google and OEMs will notice the change.
The fact that it uses Linux kernel and related features is an implementation detail, only visible to Google and OEMs.
What regular developers see is a Java/Kotlin based userland, with a native layer having a set of predefined stable APIs, which includes ISO C, ISO C++ standard libraries, a POSIX subset, GL/Vulkan and a couple of Android specific ones.
Tomorrow Android can be another Fucshia subsystem, and again, only Google and OEMs will notice the change.