Sounds like what Burgs call Dhammakāya. But you are conflating nibbāna with dhammakāya. Burgs say they are not the same. Read his chapter here: Dharmakaya, Parinibbana, Nibbana and Samsara — Advanced Vipassana
So Dharmakaya is the basic ground from which all formations appear, and Nibbāna is the cessation of all formations. Seeing Nibbāna is seeing the non-arising of conditioned states, saṁsāra is brought to cessation when conditioned states are brought to cessation. At that point awareness is like a mirror that has nothing reflected in it. It has no conditioned states appearing within it. At that point Dharmakaya reveals itself in its sky-like spaciousness: unexpressed potentiality, pure potentiality.