@SuperDicq @eric @mischievoustomato Linux is quite more than just a kernel though, it also comes with linux-specific utilities, like a quick grep of kernel.org in my installed packages:
- https://www.kernel.org/pub/linux/utils/util-linux/
- https://wireless.wiki.kernel.org/en/users/Documentation/iw
- https://www.kernel.org/pub/software/network/ethtool/
- https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git
- https://git.kernel.org/?p=utils/kernel/kmod/kmod.git
- https://hwmon.wiki.kernel.org/
- https://git.kernel.org/?p=utils/pciutils/pciutils.git
- https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usbutils.git/

And given that you can have linux binaries without any involvement of GNU… Like say your average Go program targets x86_64-linux, the syscalls are the API/ABI, GNU doesn't defines those at all.
By the way, you can entirely have multiple libc in the same system, see how most people use dietlibc for example.

> GNU is an operating system.

Which one, Hurd? That's barely a base system. Guix? That's a distro.
The GNU Project as a whole? That's very much cat herding given the lack of cohesiveness of it all, like how Guix ends up using a bunch of GNU alternatives (tcc and musl, among others) to be able to bootstrap itself.