What's the minimum size of people to ask for independence? One person, one thousand, one million?

I imagine it's dependent on boundaries not individuals. A nation, an island, a state, or a city might ask for independence, but not a person or a group of people. In the US we even have semi-independent spaces like reservations and embassy buildings where a single complex or structure is considered separate from the nation that surrounds it.

I would say, it depends.