• Sure, I should have gone further.

    Systemd/GNU libc/GNU Coreutils/GNU BASH/Linux/X11//GTK/GNOME
    Systemd/GNU libc/GNU Coreutils/GNU BASH/Linux/X11/GTK/LXDE
    Systemd/GNU libc/GNU Coreutils/Zsh/Linux/X11/GTK/GNOME
    Systemd/GNU libc/GNU Coreutils/Zsh/Linux/X11/GTK/LXDE
    SysVInit/musl/Busybox/tcsh/Linux/csh
    Systemd/GNU libc/GNU Coreutils/Zsh/Linux/Wayland/QT/KDE Plasma
    Systemd/GNU libc/GNU Coreutils/Zsh/Linux/Wayland/QT/LXQT

    etc, etc.

    There are thousands of combinations of the possible layers needed to make an OS.

    • the thing is that not all of them use systemd or bash or zsh or even X11 (servers don’t usually have X11 installed)

      All of them use a Linux kernel and many components that were originally developed for GNU, especially the C library.

      • Except Alpine & those based on it, which uses Linux but not GNU libc or GNU coreutils or GNU BASH… Just musl libc & Busybox. I.e. the entire subject of this thread is one of the non-GNU Linuxes.