Regarding what kind of milk kittens can drink in an emergency, I've learned that the following are available:
goat milk
Goat milk is suitable for kittens because it is closer to their mother's milk and allows for better nutrient absorption. Goat milk powder is lactose-free, reducing the likelihood of lactose intolerance in kittens. Goat milk can also be used as an emergency feeding for newborn kittens; however, it's advisable to consult a veterinarian or pet owner before feeding them goat milk powder.

Infant formula
Infant formula is specifically designed for kittens, but because cow's milk contains lactose, it can have adverse effects on a kitten's digestive system. Therefore, it's best not to give kittens cow's milk, but rather choose a nutritional formula specifically formulated for kittens.
lactose-free milk
Kittens can drink lactose-free milk as an emergency treatment, but not long-term. Lactose-free milk can replace other milk powders to provide nutrition for kittens, but it needs to be given in moderation.