These tests can't ever tell you what ethnic group you're from. Even that Nigeria map that cut the country into three is inaccurate in varying degrees
I don't think that is true.
My mother's hapologroup came back L2c on 23andme and National Geographic, which is Mandingo/Mandinka. Fwiw, on Ancesty.com, when you add up all of my mother's ethnic regions she came back with over 40% of her DNA from the modern countries of Ivory Coast and Mali (which includes Sierra Leone, Liberia and Guinea), which is where the Mandingos live.
My father hapologroup came back E-M263.2on 23andme and National Geographic, which comes back closely related to the Bamileke/Bamoun-Bamum of Cameroon, who are subgroups of the Tikar people. Ancestry even says on their website that:
"...
Although the Cameroon/Congo region is incredibly diverse, with more than 200 different ethnic groups, our genetic profile for the region is primarily represented by samples from the Cameroon Grasslands, where the largest populations are subgroups of the Bamileke and Bamum peoples. These tribes’ origins are not known, but it appears that in the 17th century, they moved south into Cameroon in a series of migrations to avoid enslavement—and, in some cases, forced conversion to Islam—by the Fulani peoples. Cameroon’s west and northwest provinces are the country’s most densely populated regions. The populous Bamileke tend to be Christian and live in small fons, or chiefdoms, in highly organized villages led by local chiefs. The less populous Bamum tend to be Muslim and have a more centralized social structure under a high king... ."
Learn about the Cameroon Ethnicity - AncestryDNA
So they are indicating the tribes and if that is not enough you can Gedmatch your results to find out your ethnic groups.