given that this is a launch announcement, it would seem to imply that they've started in Lagos (probably due to its relatively high density of internet users) and will expand out into other regions in Nigeria and other African nations as they grow.
Most people don't realize how big of a land mass Africa is. US fits in Africa 4 times over. It's the second largest continent after Asia.
Taking a look at different map projections when I was young was the first time I realized that visualizations can be deceptive.