Running a Raspberry Pi from an SSD is a lot faster and more reliable than from a flash card. So I bought the Argon One M.2 case for the Raspberry Pi, which has an SSD socket. I wanted to run the 'lite' version of Raspbian, as I am using this Pi as a server/appliance and have no use for the desktop environment. But how to move the OS to the SSD when you don't have access to the desktop utilities or an external M.2 enclosure? It's easy:

• Install the desktop version of Raspbian on a flash card and boot the Pi as per usual and update all packages. This will give you access to the Raspberry Pi Imager, in the utilities menu.
• Use the Imager to copy the OS you actually want to run onto the SSD drive (in my case, Raspberry Pi OS Lite 64-bit).
• Use the Raspberry Pi configuration tool to change the boot device order, selecting USB priority.

The Raspberry Pi configuration tool is run from a terminal using the command 'sudo raspi-config', then from the menu select 'Advanced Options' and 'Boot Order'. After rebooting and setup is complete, you can remove the flash card entirely, or keep it there as a backup OS.