God is not "part" of creation, so I believe only God is capable of a continuous and meaningful, eventful existence without duality. God's creation however needs duality, to perceive existence, time, space, the passing of time. Lucifer may or may not be independent of this, likewise to God.

This is like the physics at the extreme, approaching the infinite. Like the object persisting at the event horizon of a black hole - except that God or maybe Lucifer is able to observe their own precise position but we can only observe from the outside, from a safe distance.

This is why I refuse to be part of any religion. God created angles, man, etc. in His own image, but outside of God's protective Grace everything must exist in the duality and duality is corruption, winding down, ultimate destruction at the end. What survives is going to return to God's Grace, and will be able to assume that image again.