Just drinking some of this now. From the article and the ingredient list on the can, I believe the fonio is used as an unmalted adjunct, as a replacement (or part replacement) for wheat. The ingredients on the Brooklyn/Brewgooder Fonio Session IPA list the fonio as 4th, behind water, barley, and wheat. It’s a type of millet so might need crushing before adding to a mash.
It’s a nice beer, if you’re into tropical flavours. I’d like to find the hop schedule so as I could see if those flavours are really coming from the fonio or more the hops, but haven’t found it yet.