Don't know enough about africa and early america to say, the tribal norse had a hereditary mercenary group that worked for Byzantium, in the middle east persia and timurids both sent troops to help fight rome and byzantium in the holy wars, in Asia Ronin groups in japan were essentially condotteri mercenaries, as were the troops that function as Manchu Banners in EU4.
and as for large countries being unable to rent condotteri, France gave some to america during the revolutionary war, britain gave some to germany during the napoleonic wars where they didn't declare war, and the entire US involvement in vietnam was technically condotteri since we never declared war.
Wait wait here.
To begin with, a lot of your examples are outside the EU4 timeframe. Anyhow.
1. The Varangian guard was basically mercenaries/invididuals that took up employment, this is not the same thing as condottieri, which in the game is modeled on princes/states hiring out their armies for pay. Like many German princes did. Mercenaries are already covered in the game.
2. "in the middle east persia and timurids both sent troops to help fight rome and byzantium in the holy wars" <---I'm very unsure about the timeline on this, the crusades ended long before Timurlane created the Timurids, so forgive me for being confused here. Same with Persia, there was no Persia, so who are we talking about?
3. Check etymology of the word "Ronin", they were also mercenaries, or soldiers for pay. Not the same basic concept
4. "and as for large countries being unable to rent condotteri, France gave some to america during the revolutionary war" <---To my knowledge France was an ally of the US during that way, and they also were at war with Britain themselves (for different reasons)
5. "britain gave some to germany during the napoleonic wars where they didn't declare war" <--when?
6. "the entire US involvement in vietnam was technically condotteri since we never declared war" <----You never declared war because the communists were basically rebels, it was an insurrection, and the US was assisting the Vietnam government (legitimacy of that "government" can be put in question ofc). Anyhow, once again, basic concept, the Vietnamese did not pay the US to intervene, and there wasn't many war declarations because both sides were afraid of the conflict spreading (China, Soviet Union etc were assisting the communists).