You can ‘roll back’ to the image we shipped with version 0.1.7 following the above steps. If you want to create your own custom complete images as backups, the steps we used to create that 0.1.7 image are in this doc: AmpliPi/pi_imaging.md at main · micro-nova/AmpliPi · GitHub
The basic idea of it is to use dd to copy from the Pi instead of to it. They just are large images (32 GB) so we utilize the same resize-once functionality that the Raspberry Pi OS uses on first boot. So if you don’t care about that then your "backup an SSD with dd" method should be the same here. The only difference dealing with the eMMC is using rpiboot to get the disk to show up under /dev.