First, welcome to YT!
Try sprinkling a bit of parmesan cheese on the food to see if that encourages your baby to eat. The Nutrical is to help avoid the pup having a hypoglycemia attack. I just did it twice a day the first few days that Lulu came home while she wasn't eating like normal (BTW, Lulu didn't like it either...I just rubbed a pea size amount on her gums). I choose not to feed any canned food & only feed dry kibble.
Ideally, your pup would still be with her furmommy at the breeder's house at only 9 weeks old & 1.5 lbs. Most breeders like to keep the babies until they are 12 weeks old and at least 2 lbs. But, since you've already got your baby you just need to watch him very closely. He should eat every few hours & limit his playtime. This will help avoid a hypo attack. Familiarize yourself with the signs of a hypo attack & be prepared in case it does happen.
Good luck & congrats on your new baby.