Apart from a broader scenario whereby Germany is more successful/fights longer and thus either exports weapons or has more allies in Africa, perhaps the best scenarios I could see would be perhaps before the surrender/collapse in Tunisia, Germany ranges to get some Hummels to Nth Africa which are then captured and conceivable eventually end up in local use - say with Tunisia, Morocco or even Libya?
Or perhaps more are sent to the likes of Syria which then potentially offloads them further to others. The problem with this or the earlier scenario would presumably be access to spares/ammunition at some point...I would think.
I suppose an even more radical solution might be if Germany somehow retained/reclaimed its African colonies (see below) and thus had Wehrmacht and/or allied forces there which thus used such equipment. That raises potentially even more interesting scenarios and opportunities.
