Ubuntu Phone is going to be running on top of glibc and the regular GNU coreutils.
You can also stick Plasma Active from KDE on top of most phone hardware, given driver support, and get another mobile OS running on top of GNU.
The FSF isn't supposed to be an OS company. They are a foundation for free software. They wanted to make a POSIX compliant free *nix, and did. Their stuff also happens to work with Linux by design. You can take it or leave it, but they aren't a commercial entity to push consumer adoption.
You can also stick Plasma Active from KDE on top of most phone hardware, given driver support, and get another mobile OS running on top of GNU.
The FSF isn't supposed to be an OS company. They are a foundation for free software. They wanted to make a POSIX compliant free *nix, and did. Their stuff also happens to work with Linux by design. You can take it or leave it, but they aren't a commercial entity to push consumer adoption.