Indeed most Linux distros today first boot into an initrd filesystem, mount the “real” rootfs somewhere, and then `pivot_root` to the real `/` while calling init (usually systemd) these days

An important part of passing the red hat certified system administrator (rhcsa) was to be able to recover a rhel system that was failing at booting… i got that in my exam, and i suspect that’s present in every exam session.

Good times, I miss working on rhel systems.

Once you can boot “by hand” from a Grub prompt a lot of the magic starts to disappear…