How to do this with a single command without disabling BuildKit

BUILDX_EXPERIMENTAL=1 docker buildx debug --invoke bash build --progress=plain 

Optionally, you can add --on=error to only start the shell if an error occurs.

--progress=plain is important because the shell will act really weird without it

More about this: https://github.com/docker/buildx/blob/master/docs/debugging.md