Atleast on Arch, Systemd should drop you into the Emergency shell if it cannot mount a device that isn't defined as optional. IIRC it might require a root password to be set, however.
Otherwise, edit the kernel commandline to add "systemd.unit=emergency.target" to the end, which triggers systemd to straight boot into this console without trying anything that it doesn't need to bring up the console.
Otherwise, edit the kernel commandline to add "systemd.unit=emergency.target" to the end, which triggers systemd to straight boot into this console without trying anything that it doesn't need to bring up the console.