Don't know if they wrote about stoicism (don't know enough about philosophy) but Souleyman Bachir Diagne (Senegal) and Achille Mbembé (Cameroon) are quite important african philosophers, you could check theri works
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Diagne teaches at Columbia I think.
I'm currently reading Behold the Dreamers by Imbolo Mbue, she got a lot of hype for selling her book for a million bucks before it was even finished, but tbh it's not THAT great...well-written and all, but not really worth all the hype imo. Some stereotypical stuff too.
Also I just came across this free ebook :
Afridiaspora’s My Africa My City - Afridiaspora haven't read it yet but if of y'all want to download it