Raspberry Pi root on SSD

For Raspberry Pis with the root file system on SSD, I prefer to leave the boot partition on an SD card, particularly when the Pi is to be put in a case like the Argon ONE that makes the SD card inaccessible without a screwdriver. That way, the OS can be reinstalled in the future by copying the distribution image over the SD card, then repeating the transfer procedure listed below.

To install then move the root fs from SD card to SSD:

1. Make an SD card, maybe with the lite image, boot it and do the initial dialog.
2. Make an ext4 filesystem on the SSD, and copy the root file system with cp -ax /. /mnt.
3. Use lsblk -o +PARTUUID
4. Edit /boot/firmware/cmdline to change root fs.
5. Edit /mnt/etc/fstab to change root partition.
6. Reboot.
7. Install raspberrypi-ui-mods etc.