To solve WHICH African problem? I think it's hard to come up with ideas or assist you in any way unless we know what you have till now and how much strength you hold to implement the project practically.
Don't expect Africans to download a core wallet or access the product on a chain. Your solution should be like a decentralized charity that feeds malnourished African kids. Anyone sending money to the charity address must have the confidence that money will be used to serve the purpose it's intended for.
Decentralized charity would be the only way which would really help out it might not completely solve out but somehow it would really be a big help. Ive been looking for those organizations or groups that do have the same motive or project but i cant really easily entrust funds and for op he didnt mention about the exact idea on his mind on what problem hes referring to.
There are good charities working around the corner but you never know what actually happens in Africa. There are many fake charities ran by scammers where money never makes it past the United States. The blockchain based project should be able to replace these with a generic decentralized charity that doesn't involve any middle parties. Only the donator and the food distributor.
Indeed there is a ton of charities working around in the community, one of the organizations that definitely have my trust is the water project organization (
https://thewaterproject.org/). They give you a report for every donation that community makes (
https://thewaterproject.org/give-water#). So, I bet the organization really solve the problems in Africa.
Try to check that link later on. It is good to see their transparency since they do make a report which is really an obligation. @Joel i agree on what you have said it would always be good to have direct tx with donator and the food distributor but there would still be a possibility that they wouldnt apply all the funds being accumulated from donators but if they do have that real-time tally and all necessary expenses then this would be convincing and due to scams it cant really be avoided for anyone to hesitate.