OpenEmbedded is a software framework used for creating Linux distributions aimed for, but not restricted to, embedded devices. Below are pre-built console and desktop images of Debian with their respective bootloader and boot image. If desired, these images can be recreated by following the build from source instructions found here (Note: this link will take you to the Linaro Github)
Fastboot files (Advanced users)
Choose between RPB and RPB-Wayland. You will need to download the “boot image” and your choice of “Desktop” or “Console” rootfs.
NOTE: Only download one root file system (Console or Desktop). You should match the type of rootfs to the boot image you downloaded above.