I agree with giving canned. At least it's balanced nutrition. You can worry about his teeth later, and as long as he's chewing on something (bully stick, etc.) then I don't see why not
My girls both get canned twice a day, with their Missing Link mixed in, and they have kibble down all the time that they pick at. They must be eating it cuz it's dwindling down
They get yogurt with their food at night. Thier poopies are nice and firm
Plus they get bullies and hooves for their teeth, and I brush them as well. We alternate between Merrick Puppy Plate and Wellness Puppy. Their kibble is a mix of Blue Buffalo lamb & rice, Castor & Pollux Puppy Super Mix, and Wellness puppy super 5 mix. They seem to like having different bits to pick out of there
, and their tummies never get upset because they're used to eating a variety of foods.
You can try the VitaGravy, it's one of the better ones nutritionally.