So an Idea ocured to me today, not sure how viable it would be ,but here it goes;
there are several kinds of "counties" in varying tiers;
Government in Exile: control no land(or only a vary small percentage of what they claim is rightfully theirs? Taiwan's claim to be the rightful sovereign government of The Republic of China while The People's Republic of China claims they are just a province of them, though the whole "
Two Chinas" situation could require it's own system[which could in turn be reused for any other long standing/stalemated civil war]), but can try to gather support to retake the territory they previously ruled from other nations(should have their own sub-menu/screen in the Diplomacy tab?), this government form could also be used for landless international organizations.
Rebellion/Revolution: controls some land, but isn't widely acknowledged as the rightful ruler of that territory, in addition to representing revolts, this is also used to represent parts of counties that are not under their government's control, such as African warlords, Mexican drug cartels, indigenous tribes and so on. if control is maintained long enough(and they are the proper type of "rebels") they may form a proper nation from this territory.
Nation: what you'd expect to play as in a PDX grand strategy.
Union: a network of "autonomous" subjects/member states, the scale of this autonomy can vary greatly and change over time, it would be something of a mix between Stellaris's Federations and EU4's HRE.
Examples of Unions would be The British Empire/Commonwealth(and maybe the other remaining European colonial empires as well, this makes decolonization easier, but also removes changes in how the new independent nations are shaped if they're all "premade" that way [the India/Pakistan split for example, though setting up all the separate Indian
Princely States and then using special decolonization events to merge them together could work]), The Union of Soviet Socialist Republics(Russia and her Satellites/puppets), and could also be used for the People's Republic of China(split into its many provinces,
Hong Kong and Macau[which would be transferred from the British and Portuguese Unions in events/diplomacy?], and allowing Tibet to be "integrated" while retaining some its identity, and maybe some interesting mechanics for the previously mentioned "Two Chinas") and the USA(The 50 states, D.C., some of the larger
Indian Reservations, and the
Overseas Territories[which could include the Philippians at the earlier start date(s?), though trying to keep them and possibly integrate them as a State would be a pain, after all making Porto Rico the 51st State still hasn't happened], though the uninhabited islands could maybe be integrated as part of D.C. or the nearest State/Territory for simplicity's sake).
Unions could also be used to represent diplomatic systems like the EU and the UN, possibly enabling those organizations to develop into full fledged political entities of their own if enough influence is accrued/given to it from members