There is no such thing as a genuine mint, unused, African plate. There are some collectors who specialize in African plates and they can testify that genuine, used African plates are always in fairly poor condition.
The Sierra Leone commercial vehicle plates in this photo were mostly sold by German Ebay dealers rui_marques with a couple from schilderstadl and they have almost certainly come direct from the factories in Germany. They have never been near Sierra Leone although they do have correct registrations. They do not have the correct validation sticker on them that is always used in Sierra Leone.
Similar mint samples are also known from Ghana, Lesotho, Liberia, DR Congo and Cameroon.