Is the puppy being sold from a reputable source? Unfortunately we do read all the time about puppy mill puppies being convincingly being sold through fake homes. You only have to see how many breeding bitches are being given to rescues like Manytears, to know that it is still going on.
If you are paying the going pedigree price, then i would expect PRA and FN history. Do you have access to a Kennel Club five year pedigree of the puppy or it’s parents? You can check up on the health results of registered dogs , voluntarily given . What information has the seller given you and have they got the whole puppy family , a shame the parents haven’t been tested.
It’s a lottery, there are other conditions that are common, or they can succumb to something unexpected at an early age like my beautiful boy who had another kidney issue.
FN is an early onset condition, usually by four I think, so if the parents are older, then that is positive. If you are happy with everything, and know the sellers, just consider the price of the puppy, and try not to fall in love with it till the decision is made.