Thought Experiment.
What if ...
850,000 small cities with approx 10,000 people in each city?
Each city living in symbiotic harmony with the surrounding environment and cooperating and sharing with those nearby. All residents cooperating and sharing with each other.
As an alternative to giant megacities with millions of people all stacked on top of each other competing for jobs & other resources.
I can't visualize the habitable space on mother Earth, so I have no idea if this is even viable.