Should already be in the game:
Greece
Ukraine/Cossack
Greece is badly needed to replace Italy and Malta’s terrible revolution options and Ukraine is a must once Poland is in.
Nice to have:
Belgium
Norway (including Iceland)
Livonia
Ireland
Solid options, but Europe is already extensively covered so I could take it or leave it with these ones.
Is a civ or should be a civ:
Poland/Lithuania
Italy
Sweden
Somalia
Kongo
Ceylon
It just feels wrong to revolt into an already existing main civ. Yeah that happens with USA and Mexico, but they were the quintessential revolutions long before being full civs. Them being full civs is what’s out of place. Doing this would also be opening up a can of worms, since everyone and anyone revolted at one time or another. Dutch should revolt from Germans, Portuguese from Spanish, almost everyone from France, etc.
Should never be a revolution:
Holstein
Minor border regions are not at all appropriate for revolutions. Otherwise every single rebellion in Europe and beyond is going to be on the table. The only exception to this would be Corsica which actually had a fairly impactful revolution.
Missing:
Pirate Republic (Jamaica could be fun but this would be more broadly applicable)
Northwest Confederacy (could provide an avenue for North American natives to get advanced technology in a way that makes sense)
Taiping Heavenly Kingdom (Could go along with Tungning to have multiple Chinese revolutions)
Tatars (central Asians rebelled against Russia many times)
Arabs (Trucial States or Wahhabis)
Sokoto Caliphate
Zanzibar
Liberia (both Zanzibar and Liberia can represent colonial outposts without displacing what should be proper African civs)
Existing Revolutions
There’s definitely a lot of revolutions that could be shifted around. France could have Mexico or Chile, Portugal could have Canada, etc. Italy should not have USA, Malta shouldn’t have Hungary, and British should not have Haiti. I do think Argentina is a good fit for Germans. They did have quite significant German immigration and will always have an infamous connection to Germany even if that mostly comes later.