If you target mobile and your app/site can work on slow connections then the market is huge. For example South Africa has about 20 million users(out of 50 million) with some internet access but only about 5-10 million has broadband.

South Africa and Kenya has good and fast internet in the cities and large towns.

Don't expect to use AWS or Azure because none of the mayor cloud providers has a DC in Africa. So hosting local is advisable otherwise you incur latency of at best 180ms.