This argument is very flawed because it assumes that the presence of GNU software is what makes GNU GNU. Imagine you have GNU+Hurd. And you replace 99% of its components with non-GNU ones. Is it suddenly not GNU? Or is it a "Hurd distribution?"

Let's go deeper. The BSD userland can be combined with Linux. Is it suddenly Linux? No, it does not work like desktop Linux-based systems at all. It works like a BSD. What about GNU+kFreeBSD? Is it suddenly FreeBSD?

As long as a userland is tied to some crucial component, it is a seperate OS. In BSDs and GNU+Linux it is the C library. If you have a C library, everything is tied and locked to it basically. Except filesystems. But you can have these filesystems on Android also. It just needs to load the correct kernel modules.

Android can't run GNU software natively anyway. It needs a compatibility layer. Like Termux.