TL;DR -> No, not really
On the plus side, a sauna can get you accustomed to sweat. But a typical sauna session of 20 - 30 minutes will not include the activities you would undertake in a visit to Africa. It's also not the same kind of sweat you get in a tropical environment.
Some evidence for acclimation is given by examining how the military trains soldiers for desert operations.
For Americans, this involves rotation to the Fort Irwin National Training Center (in the Mojave Desert, shown in the photo above) for exercises that simulate a deployment. British troops also use the same facility. The British army also trains 3 battalions a year at both desert and tropical locales in Kenya.
And the archetype for desert deployments, the French Foreign Legion, trains in the field at Djibouti.
None of the training regimens above indicate that a sauna is an acceptable substitute. This includes training for their tropical counterparts. Same thing for football acclimation.
Military training is not discussed because it is recommended for you. Instead it is discussed because it is one of the logical sources of how people train for harsh environments. If these regimens used saunas, then the answer would be a trenchant 'YES, because there's a body of credible evidence on the ground indicating that saunas work'. But instead, neither the military nor athletics use the sauna to train for harsh environments.