I disagree. It's running gnu apps on a real Linux kernel. It produces an glibc API for application code. The only unusual thing from a gnu/Linux point of view is the hybris and bionic layers, but that can all be thought of as a very bizarre glibc implementation. The only really nonstandard thing I can see is that /proc is not visible, so utilities that pull information out of there don't work (at least under Android Oreo - I think /proc was accessible in earlier versions of Android).