Yes maggots do make great chicken feed. A common trick is to stack, say, possum bodies, roadkill etc on a wire rack above your chickens head height, and they pick up the maggots as they fall.
I tried it once. Frankly I don't like the smell or look of dead things. Also, basic fact, no "Energy Conversion" is totally loss-less, and although the maggots are higher in protein than possum meat, more is lost in nitrogen gasses, and the odd "One that Got Away".
So now I feed the meat straight to the chickens (cooked). Mostly offal meats from my sheep. Occasional supplementation with possum or eel. They do much better on this than on the few yucky squirmies they actually got!!