City-states are not comparable to modern nations in their scope, budget, police powers, military powers, surveillance powers, etc. A return to smaller political units that don't have the resources to mount, for example, pervasive surveillance and large-scale incarceration might make us freer than we are now.
In other words, maybe national politics needs to be refactored into smaller units to be more tractable and maintainable.
"A return to"? You make it sound like the empires of old simply couldn't be oppressive, simply because they didn't have hi-tech surveillance.
Not to mention that industrial-scale slavery existed in quite a few places well before the modern era. "Returning to" the ways of the past is very much not guaranteed to reduce our oppression.
In other words, maybe national politics needs to be refactored into smaller units to be more tractable and maintainable.