Africa does not have a toilet problem. Or a tech problem. Or even a resources problem. They have a lack of intelligent social organization problem; i.e. dysfunctional or non-existent institutions, laws and organizational structures, as well as myriad forms of corruption from top to bottom that make it impossible to create the systems that would otherwise keep them healthy, sanitary, safe, well-fed yada yada.
Maybe he could publicly ask, how every year, the Minister of Finance in Nigeria publishes a note indicating there is somehow billions of dollars missing from the coffers, that didn't make it over from the Ministry of Petro Resources, i.e Oil [1]? Or the like. Tackling the more obvious, glaring wide-open 'in our faces but we ignore anyhow' forms of corruption might be a good start, and would ultimately yield a lot more than functional toilets.
[1] https://www.theatlantic.com/international/archive/2016/03/ni...