Citizens are not the unit of democracy--they are not even vaguely democratic entities or actors, they are much more complex than democracy methods could manage. People are irrational, aesthetic, spiritual beings who make personal decisions based on unknowable, undiscussable, uncountable and unaccountable influences. Democracy is not meant to handle this level of variety. But it is fit for simpler situations.
Neighborhoods are the base unit of democracy. Simple joint agreements among individuals and households to support the basic needs of living together in a shared space and place. Democracy beyond the neighborhood should only concern things that neighbors cannot decide and take care of. The trick with more remote attempts at democratic decision making is that it becomes difficult to know enough to make good decisions--because an understanding of one or more levels closer to neighborhoods as well as understanding of one or more levels more remote beyond the level charged with making "democratic" decisions it required.
The messy business of polycentric decision-making (Polycentric Governance) comes into play if decisions are to have the right amount of understanding (requisite variety). This means that all the parties needed to make good decisions are selected based on the nature of the decisions not on any pre-existing structure. It truly means forming structures fit for decisions, not lame attempts to slot decisions exclusively into pre-existing and prescribed structures. Of course use existing structures if they have requisite variety; but always ask whether they do or not before entrusting important decisions to them.
This line of thinking brings up questions about neighborhoods having votes on certain issues rather than individuals across neighborhoods. It also brings up questions of weighting of votes. And votes by places and their weighting.