Problem is, Linux is not GNU. A Linux distribution may contain elements from the GNU project, but then it'd be better to use the name GNU/Ubuntu or GNU/Fedora. Android is most definitely Linux, and most definitely not GNU. Debian is almost wholly GNU (except, of course, for the Linux kernel, which is most definitely not GNU). A Fedora distribution will be somewhere in the middle, and any given Arch implementation could be near 100% GNU or near 0% GNU. Ultimately, just saying a distribution is GNU/Linux is misleading, because you really don't know how much GNU is in there. (Whereas Linux either is or is not in there for certain.)