Would you keep a "perfect" yellow pup if it had everything but great pigment? Nose is black but eye rims just light black and lips a little light in spots.

I know this is a serious question to you, but ...in the big scheme of things , this isn't even on the list of reasons not to keep a puppy. The pigment will come, will this baby likely have snow nose , propably . But really, there is no such thing as perfection, and it sounds like you are looking for it. Be prepared to beat your head against a brick wall for many years. So...if this baby has a clear CERF , and has nice structure , that is all you can ask of a baby. So many hurdles to cross , major hurdles, that your worry doesn't even enter the picture.

I would keep her. I have had pups continue to get darker through 5 months. When she is an adult, if her color is still not as dark as preferred, you could try giving kelp. I have heard that it should not be used on puppies.

Pigment can take several months to come in all the way. I would not let that be a deciding factor if you are talking about a 7-8 week old puppy. If the parents have good pigment, then most likely so will the puppy.