Sadly, unlike 10 years ago where you could just turn up, African operators are now bound by government restrictions which protect the local pilots by restricting how and when you will be allowed to fly in your chosen country as a foreign pilot. It is no longer walk-in, but based your number of hours. In countries like South Africa, they simply won't give you a visa at all.
Botswana, Kenya, Zambia, Namibia and Tanzania all now enforce stipulated hours you must have before the civil aviation authority of that country will convert your license to their own. It is between 500 to 1500 depending on the country, (you can look up the hours on the CAA websites). As a new pilot, you'll have to get these hours elsewhere before coming here. The result of this is that when operators do hire outside their country, it now comes with very high hour requirements in order to get over government minimums.
And, when they do hire foreigners, the are now coming from the region. E.g. a Tanzanian operator last year really needed pilots, and so their latest cohort came from surrounding Kenya, South Africa, Zimbabwe etc. Regarding conversion time for licence, it will depend on the country, the general standard now is that you must fly 500 hours in a local aircraft before being given your converted licence.
The continent has changed a lot, and local interests are now prioritised via a pro-African workforce, so it is important to be mindful of the existing challenges that you may find if you're aiming to look for work here after flight school. In summary, you can work here, but not at the beginning for your career, it would be after 1000 hours or more.