The current automotive images are not compatible with bootc. We hope to eventually change this, but that needs some serious engineering work.
The approach for image updates in automotive is based on ostree. automotive-image-builder builds ostree commits, as well as an initial physical image containing that commit. Once the image with the initial commit is deployed, ostree is used to do the update. This happens either by pulling from an ostree repository or by side-loading an offline update file (an ostree static delta) using whatever mechanism you have available.
Here are some some docs explaining how this works:
Also, in general the approach we the automotive images use is to produce physical images that are flashed, we don't use installers like anaconda. Installers are not really a good fit for embedded style hardware.