Any uneaten bits of wet dog food might turn rancid which would promote unhealthy bacteria. Don’t know if they would eat dry dog food as I never tried that. When I as raising mealworms, I fed them carrots and bits of cabbage. Both these provide both nutrients and moisture, but unless you’re keeping mealworms long term, as long as they’re alive they’re nutritious without adding any supplements. Dusting worms with calcium is a good thing for the birds, but unless you overfeed worms to the extreme, it’s not necessary.