Hi Henrik, thank you for your interest in our WordPress Page Builder!
The layout management tools provided by the Post and Page Builder are directly integrated with TinyMCE and unfortunately do not allow you to work with Gutenberg blocks inside of the Post and Page Builder content at this time.
That being said, our team has been reevaluating how our builder integrates with Gutenberg and it is possible that we will have increased compatibility with it in the future.
I hope that you will be able to find a builder that provides the tools you are looking for and please let us know if you have any other questions for us!