cacao is full of magnesium, zinc, iron, stearic acid (hard waxy fat) and theobromine, which is a drug in the same family as caffeine, in fact when you drink coffee, the liver converts 12% of the caffeine into theobromine. it dilates the blood vessels and bronchi in the lungs, so i think it's probably better for exercise than caffeine. it does take longer to absorb though, about 3 hours, because it's very oily.

regular "cacao powder" is actually the waste product of solvent extraction of cacao butter, which is used with milk powder and sugar for white chocolate and then re-mixed with a smaller amount of the cacao powder and shitloads of sugar and powdered milk to make regular milk chocolate.

the best form of it is quite expensive, the raw, roasted beans, but second best is these beans powdered up and melted and pressed into little drops, at least that's the form of it i can get here in portugal that is just cacao. best to read the label carefully, you probably can find a similar product. it contains around 57% fat, iirc, and it's a great source of fats for a keto diet. once you get used to eating the raw chocolate you will never feel the same way again about even dark sweetened chocolate. sugar contaminates it!

btw, another one that is pretty good is maca, though i think that varies a lot. i had a powdered form of maca that seemed really good but a standardised extract i'm taking at the moment doesn't seem to do anything much at all.