How to care for an orphaned puppy?

Puppies cannot eliminate (urinate or defecate) on their own until about 3 weeks of age. They rely on their mother to stimulate their reflex to initiate elimination. Orphaned puppies, on the other hand, rely on their caretakers to stimulate them to eliminate." Puppy being unable to defecate could be life-threatening - if you can see a veterinarian, do so as a matter of urgency.

Reference: https://vcahospitals.com/know-your-pet/feeding-orphaned-puppies

This is also good reference: https://resources.bestfriends.org/article/caring-orphaned-newborn-puppies-basic-care-feeding-and-disease-prevention