I mean the Cape Flats (where all the apartheid-era Black and Coloured suburbs are), which I read is basically sand. The areas further east are more fertile and perfect for vineyards and other Mediterranean crops. In fact, I could very easily have seen the French colonizing South Africa, and it'd fit as the coast around Cape Town looks like the French Riviera (and I have a bit of a soft spot for a French Cape). I think that the French would have done quite well in The Cape, and hopefully whoever runs the French colony wouldn't be as strict as the VOC (who actively discouraged white settlement and wanted to keep the Afrikaners dependent on them if I'm right).
BTW, have you checked out this timeline? https://www.alternatehistory.com/forum/threads/lantarctique-a-french-protestant-south-africa.438212/
The VOC weren't interested in expanding the colony beyond a certain point (although there was a point in the 18th century when they asked the Governor (van Plettenberg?) if he wanted retired soldiers from Europe or slaves from the Indies (guess which one he chose). The VOC was big on wanting to make money but bad at being willing to spend it to maintain/secure their investment. Which is why it took more than a decade to get them interested enough to build more than a stockade fort, two-three before they actually started allowing "settlers" (and even then, they were almost as strict about who as the Castilians were about the New World). To their mind, more settlers were bad, since that would mean the Cape settlement would expand. If it expanded, it would need protection from natives. Protection meant soldiers that the Compagnie would have to pay...etc etc ad nauseam.
And I also have an interest in a French South Africa (Lord knows, we got enough of their Huguenots OTL. Hence place names like "Franschoek" and surnames like "Du Plessis" and "Fouche" etc. Hell, when I had to get my passport to go abroad, what do you know, it was issued in French) , though while it may have expanded sooner than the OTL version, I suspect it would be regarded similarly to Quebec or Louisiane (look at their settlement of such a large area over 200 years, and I have my doubts that an Afrique de Sud would fare somehow better. Cape Town would probably wind up as New Orléans/Montreal-type - major port but a relatively unsettled hinterland).