In the Worlds
RPG book, Nausicaa was the centre for the Nausicaans but a government didn't play much of role.
In STO -
(I know, I mention this particular game in every second post by now, but it is a handy alternative source and there's nothing against a bit of creative cross-pollination.)
- the Orions and Nausicaans are major factions, even though they've been uprooted from their homeworlds. They have their own ships (lots of them) and provide the Klingon Empire with significant personnel, even adding their ships to the KDF.
To bring it into perspective: Melani D'ian, an Orion, assumed power of the Orion Syndicate and conducted an ethnic cleansing to bring it back into the hands of the Orions. She made a deal with the Klingons: The Orions left their homeworld and reselled on Ter'jas Mor, a planet in the Klingon Empire the Syndicate could rule as vassal state.
The Orions joined the Klingon Empire in 2394. The conquest of the Gorn Hegemony added the Gorn and their contracted mercenary allies, the Nausicaans, to the ranksof the Empire in 2403. The Letheans negotiated for entry into the Empire but the Klingons made it low-priority. (STO: The Needs of the Many
In 2409, the Ferasans, aggressive descendants of the Caitian diaspora, part of the Ferasan Hierarchy, joined the Klingons as well. They a playable species and do not exist as non-playable factions, though.
However, recently Gorn rebels have appeared and there are hints here and there that the Gorn Hegemony, currently a vassal state to the Klingons (King Slathis has a non-voting seat in the High Council) might attempt to break away sometime. (I hope so. I always thought the Gorn would make terrific Federation allies.)
If the developers ever desided to introduce the Typhon Pact to STO, its makeup would be noticeably different.