I really like the way you have opened this conversation because many people still see blockchain only as a tool for trading and investment while forgetting that it is a foundation for solving real life problems.
For me one dApp idea that could be powerful in Nigeria is a transparent government spending tracker where every budget and every contract awarded can be viewed by the public on the blockchain from start to finish so no one can hide or change the records this could help reduce corruption and improve accountability.
Another idea is a decentralised land registry where property ownership records are stored on the blockchain so no one can forge documents or illegally sell land it would also make it easier for people to verify ownership before buying property