Is Saguna Brahma not the Cosmic Mind including the whole of its projected universe?Saguna Brahman can be "one God." However, Nirguna Brahman, in my view, is not.
Nirguna Brahma is beyond that, so can never be grasped by any human mind (or indeed be called God).
So, if there have been or still are expressions of God in the universe, They must come from the tangential line between the two (called Taraka Brahma), belonging neither to Saguna nor to Nirguna but forming the bridge between the two.
Without the grace of such a bridge an individual entity can never escape from Saguna Brahma.