Before listing any specific manifestation, Krishna states the most fundamental truth. I am the Self seated in the heart of every being. Not somewhere far away. Not in a particular temple or heaven. Inside every living creature. That is the starting point of the entire vibhuti catalogue.
Then the scope widens further. I am the beginning, the middle, and the end of all beings. Birth comes from the divine. Life is sustained by the divine. And at death, the being returns to the divine. Like clay that is shaped into a pot, serves its purpose as a pot, and when the pot breaks, returns to being clay again.
The address Gudakesha — conqueror of sleep — honours Arjuna's alertness and courage. Krishna is sharing the deepest knowledge with the most wakeful of his companions.