Bootable containers on the Raspberry Pi

The question on how to use bootable containers on the Raspberry Pi (or other single board computers that have ‘interesting’ boot setups) comes up quite regularly. For a while now it has been possible in image-builder to create a Raspberry Pi compatible partition table. I don’t think this has been written down in long-form anywhere except answers to GitHub issues and Matrix chats. Let’s write it down in a longer format and go over the specifics and what will make it easier in the future.