Syria is purple, and Venice is more aqua than blue. Kazakh is teal, Sibir is pretty much grey. Oman is grey, not blue.
If you want to pain the world blue in a MP co-op:
1. France: for obvious Euroblobbing.
2. Anything that can form USA: You want it reasonably quickly (technically you can do it with virtually anybody, but Portugal or an Irish minor with big DIP are your best bets for doing it fast, or maybe Friesland with France's help to not die since you can re-elect yourself into the ground to get DIP 7 fast)
3. Ethiopia: They're Muslim tech now with a god-tier ruler and fast access to religious ideas to feed vassals and build a miltech lead.
4. Sweden: Eastern Euroblobbing done with ease.
5. Bengal or U-Tsang: Pick the latter if you want a republic.
6. Brunei: Send Bengal into India and you can do more SEA/Ming, or split Ming.
7. Kazakh: A bit lighter on the blue so optional.
8. Tlemcen: If you don't want Ethiopia on all of Africa, use this guy in the west or even a western Sub-Saharan, shouldn't matter.
9. Siberian Clan: One of them is light blue. Start with trade ideas so you can conquer Yeren and Japan with the extra naval FL and money for galleys (trap units in islands to beat Japan).
I don't remember if there's a South American nation with a blue color. Are any CNs blue other than USA? Someone could just form one in SA or move there.
This would make it overwhelmingly, pathetically easy to paint the world blue

. Green is an even easier color; pink and orange carry a bit more challenge since there are no Euro majors that use them. White is pretty weak after Austria, too. Red is somewhere in between.