Yeah for my case it was easier in the initrd otherwise I’d be trying to roll back the active / partition.
Re run levels, they were a sysvinit thing so I wasn’t sure sure about systemd, this suggests that would work though https://fedoraproject.org/wiki/SysVinit_to_Systemd_Cheatsheet
And if you have to bail out even earlier, run level 1 will give you the rescue.target
Pass something stupid via your bootloader so it aborts boot and dumps you in an initrd busybox shell. No usb required.
This was my poor man’s boot environments when I was using zfs on root. I had a pacman hook to snapshot before package transactions, then if it became unbootable I’d interrupt the following boot attempt, edit my grub command line with something wrong so I’d get dumped in the busybox shell, import my zfs pool and roll back before finally rebooting again.
I’m an
atools kinda person