It is always worth keeping Bremermann's limit in mind when anyone talks about general AI being impossible. We are so far from it (as humans) that to even have an opinion about what is possible seems silly.
I think having the opinion that AGI is possible is quite reasonable given the existence of humans. I happen to believe its' advent is inevitable. I don't see how humans won't come to invent an AGI at some point in the future. Consciousness is a physical information process taking place in a physical universe. Any other attempt at explanation is woo woo.
Intelligence and Bremermann's limit are pretty unrelated. Most people have what they consider to be intelligence and self-awareness with a system that uses a lot fewer atoms than are contained in this universe. The worry, with non-human intelligences, maybe trying to bootstrap themselves to be able to take advantage of this universe's computational capacity, is with what a person once apocryphally said: "The machine does not love or hate you, but you are made of atoms it can use for other things.”