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
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