That would just be breakfast cereal with added protein. The only reason kibble for people isn't a thing is because it doesn't need to be a thing since people already eat basically the same thing but with less nutrition and more attractive branding, while "efficient nutrient and protein content food" is its own genre of grifter slop, mostly in the form of "meal replacement shakes" which companies charge a premium for.

Past that, there's the fact that nothing is ever going to beat raw ingredients on price efficiency: if you're not buying luxuries like meat or any pricier ingredient that gets used in large quantities at once then raw food is still very cheap. Things like flour, rice, potatoes, onions, tofu, oil, etc are all very cheap per meal a given amount goes into. At the price point where premade slop worse and cheaper than junk food would start to have a place, it's having to compete with people performing the barest minimum amount of food prep labor to make something better and cheaper themselves.