yes, few. there must be thousands of species mentioned in st, and you listed about a dozend forms of governments. there are more on earth any given moment with some 200 nation states.Few? The kind of major ones have a Federation, two Empires, a Union, a Confederacy, an Alliance, a Third Republic, a Hegemony, an Assembly, a Dominion, two Collectives, a Sodality, Nineteen Tribes, a Hierarchy, a Cabal, and a Council.i've alway wondered why they used so few forms of government. there never was a commonwealth, kingdom, republic, principality, despotate, and nothing with the term 'free' in the title.
'third republic'? you forgot 'Consortium', 'Coalition' and in the novels, there is another Republic, The Thallonian Republic which replaced the defunct Thallonian Empire. and the Romulans fractured and became the RSE and the Imperial Romulan State.