On the ahistoric portion of the flame nade, while I agree flame nades are fantasy, molotovs were used by all armies and they were common. If Volks had the ability changed to molotov it would be historically accurate, although it would be weird that it was different from scripts.
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? White phosphorus grenades did exist and were often carried by troops. In anecdotes you normally hear about them when they were struck by bullets and burned the person carrying them before their mates mercy killed them.