I will offer a second positive but more reserved data point. It took me closer to a day to get my custom Bazzite build working.

Switching over to my images using bootc failed because of what I eventually tracked down to permissions issues that I didn't see mentioned in any of the docs. In short, the packages you publish to Github's container registry must be public.

Another wrinkle: The Bazzite container-build process comes pretty close to the limits of the default Github runners you can run for free. If you add anything semi-large to your custom image, it may fail to build. For example, adding MS's VSCode was enough to break my image builds because of resource limits.

Fortunately, both of these issues can be fixed by improving the docs.