How to inspect state of a crashed build process?

[richard-hajek]

I am working with Docker and would like to interactively debug the last cached state of the build process' container. In legacy builder, that was as simple as starting a container with image of the cached build step. With BuildKit however, Docker doesn't natively have the cached containers in the docker ls -a. But BuiltKit has proven to be somewhat unintuitive to me, and I can't find a way how to do that in it.

How do I do that? Can I export a last cache step in BuildKit to a docker image?