focus on trying to unify Sub-Saharan Africa, then all of Africa.
The best thing you could do if you want to become a world power is to create a Unified African Identity (instead of seeing yourself as "Nigerian" see yourself and other countries as "African" and soley African), similar to how the Germans had their unification and the time to develop a sole "German" identity.
Africa's biggest curse is that there is too much infighting between countries and even members within countries for anyone on the continent to even worry about projecting power outside of the continent.
But it would never happen in our lifetime, any country that might become to powerful would get hammered down by outside countries for trying to change the status quo.
Or fighting wars of aggression take your pick