Hi folks, great work on getting this fixed. I'm using this successfully in my development environments along with the patch in ✨ Add a Normalizer and Denormalizer to support Layout Builder RTBC to propagate layouts.
I've run into an issue that may or not be related. If the original content type for which the layout builder is enabled is imported into a new environment, the layout builder setting is ignored. So I find myself having to manually enable the layout builder across environments. Once I do, then the import process above will work and I can see my custom layouts. Is this a bug perhaps?