African American has always been a funny term to me. The children of African immigrants who were born in America are African American as well. Even if they’re white, technically they would be African American.
No they are not. If an African American is working and living in Nigeria with their African American spouse and they have a child while in Nigeria that would not make their child a Nigerian. The child would be Black just like the other Nigerians, but the child would not be a Nigerian.
An African American is specifically a person whose ancestors were enslaved in the USA or its predecessor British North America. Oddly enough there are Africans who are African Americans, but those are the ones whose ancestors were returned to Sierra Leone and Liberia after the English lost the American Revolution.