1) you create an container image based on the upstream image that supports bootc, using a Containerfile that serves what ever purpose you want.

2) you push that container image to some registry

3) you use the bootc image container to create an qcow file from the image you have built (or you install the image on a bare metal system)

4) you boot up the virtual machine or bare metal system, which now includes "bootc" utilties too

5) from this point on you can update the container image you have created in step 1) and you automatically roll forward the booted virtual machine or bare metal system to the latest image you have relased (or rollback, if your updated image breaks stuff) using the included bootc utility

Currently the image that supports this seems to be limited to centos:stream9, or rhel9:

https://www.redhat.com/en/blog/image-mode-red-hat-enterprise...