Most methods of logging in require temp files. The fewest resources required would be via the serial console, which does need the USB-to-TTL serial UART cable (3.3V logic level).
More detail about rescue via clone and restore-from-edited-clone can be found here:
https://forums.developer.nvidia.com/t/jetson-wont-load-up-after-configuring-spi-functionality/112139/4
Clone/restore is a long process, but it isn’t a bad idea to keep this around as a backup in case something does go wrong. Clones can be occasionally refreshed via rsync if desired.