China doesn't need African foot soldiers to burn away in the trenches, there are enough Chinese people to serve as cannon fodder. Sounds harsh but that's the ultimate advantage of China compared to any other military except maybe India's.
What the Chinese are doing actually is to ensure they control the world's reserves of uranium and rare-earth metals. Or, if they don't control it or the governments by puppet/bought governments directly, then by extortion a la "you give the West their uranium, we grind your economy to a halt". Or, by controlling the shipping ports in the sea countries of Africa so that resources from the landlocked countries cannot be exported, or at least the transport cost rises.
The latter strategy they are also pursuing in central Europe - they bought, for example, the port of Piraeus via Cosco.
Whoever crosses their path can be ground to pieces if the Chinese wish so. The West is too f...ing dependent on China and that's gonna bite us in our behinds.
Focusing on the levers of control given by corporate control of strategic foreign sectors ignores the ability of host countries to unilaterally seize control of those assets at their own whim. China's hold over Africa is a very tenuous grasp at best.
There is a key difference between the Marshall Plan and China's modern African investment. The Marshall Plan was pretty emphatically a plan to help coerce Western Europe into supporting what effectively became the West, and combined vigorous restoration efforts with criterion for supporting certain kinds of economic reforms. In particular, it was very much meant to build up Europe not so that it served as a market for American goods but rather so that Europe could be useful junior partners in a coalition. China's current investment hews much closer to neocolonialism: it's building African infrastructure, but managed by Chinese, owned by Chinese, and even built by Chinese imported for the labor. It is not engendering local goodwill for China, and unlike the Marshall Plan, it isn't helping move these countries into China's camp in a putative global war.