Yes, but the theory of the development stage is not that "if you imagine that everything is a mandala it will become a mandala" rather it is "everything is a mandala use your imagination to discover your natural state".
Actually, in gsar ma schools that is exactly what creation stage means -- if you imagine it is a mandala, it becomes a mandala. This is why it is called "path of transformation". We are transforming our impure vision into a pure vision. We do this to undermine our tendency to engage in afflictive attachments. If we see everything as pure, we will have less grasping. The creation stage is conceptual, not non-coneotual. The completion stage is used to cut attachment to conceptuality of the creation stage. Eventually, we are supposed to unify creation and completion so that we are in the state of the union of illusory body and luminosity aka mahāmudra.
This is partially why one finds criticisms of the two stages approach even in Mahāmudra upadeshas.
Guhyagarbha contains the view of Dzogchen, this is why the thirteenth chapter of Guhyagarbha emphasizes that the mandala has always been naturally formed [ye nas lhun grub] . So it is a very different approach. It is not really the approach of the two stages.
You are so conditioned by Anuyoga, you have a hard time relating to mahāyoga in and of itself.