Isn’t android a fork of the Linux kernel wrapped in a whole lot of Java? It unquestionably dominates its market, smart phones and it’s-a-laptop-and-definitely-not-a-netbook kind of devices, but even as a Linux variant, it seems very much in its own little world. Not the most popular commercial Unix implementation so much as the most popular OS ever, that also happens to be more Linux-like rather than Unix-like.
Its primary interface with user/developer is indeed JVM based languages. However, Android is more than that. It is a capability-based microkernel-like OS implementation on top of Linux. Everything in Android goes through IPC. Every process is heavily isolated using SELinux and permissions including drivers.
