Wheat is just one of the types of grains, and grains are just one of the classes of food. So this chart, while useful by itself, shows just a glimpse of what we consume.

Here's a density map showing cropland:

Source: https://www.innovationnewsnetwork.com/relocation-agricultural-land-could-greatly-reduce-carbon-emissions/19284/

This shows that there a relatively tiny fraction of the land that currently has a whole lot of farming on it, and then there are areas where there is crop farming but less of it, and then the vast majority of the world has relatively little to no crop farming.

Africa has a huge chunk of the earth's land, and while there is a fair amount of the land used for crop farming, there's great potential for further crop farming in Africa -- without even needing irrigation or dislocation of people living there:

Source: https://www.grida.no/resources/7868

But growth in agriculture doesn't just happen because there is suitable land. And for reasons, growth in crop farming / production in much of Africa just has not met hopes and expectations.

Here's a great feature in National Geographic that shares examples of this:

The Next Breadbasket https://www.nationalgeographic.com/foodfeatures/land-grab