I believe that it is, honestly. Puppies would naturally eat the same stuff as adult dogs (raw meat and bones)... just in larger quantities to support their growing bodies. A lot of nutritionists discourage feeding puppy food because it is so high in calories and calcium that it can cause dangerous growth spurts.
Fozzie was raised on prey model raw, supplemented with an all life stages kibble, and grew up very slowly with no growth spurts. He has really good structure, for a wonky Corgi mix, and that's important. I did NOT want him to grow up to have any joint issues or bowed legs or other ailments that I've seen in dwarf dogs, especially mixes.