More like the military governor of a port city. Even if Starfleet isn't a military organization, the Bajoran Militia most definitely is one. And by means of the Bajoran soldiers under his direct (even divine) command, Sisko exercises legislative, executive, and judicial power at the equivalent of a municipal level, even extending over the civilian population of the station.

I want to see the timeline where Sisko declares DS9 an independent state.