No, not a fictional country. There has been several advanced civilizations on the African continent over the last several thousand years.
For most authors, a character from South Africa (ex: TV's Trevor Noah) is the easiest to write, as they're typically conversant in English and often have Western educations (even if they've never been out of country before).
But this is another case of there being too few SOL author's familiar with the requisite experiences. You can offer yourself as a contributor (i.e. an SOL editor reader to provide background for African characters anyone might wan to write), but it'll likely be some time before anyone writes one. :(
As I've stated before, I've 'unpublished' my entire 6-book series in anticipation of rewriting the entire thing using a black (non-African) character rather than the lilly-white atheist Alex. (It just seems like a more 'believable' character, as his reasons for 'not believing in the white man's God seem more reasonable (less arbitrary) than my original story.