I think you're setting the bar too low at 10 years. I think getting them beyond 12 is very rare, so those are the dogs that are special.
My last one made 11 before cancer got him, and he started out life as a starved, emaciated adolescent, with pneumonia.
We rotated good kibble for him (Prairie NV, Wysong, and many others), but he also ate a lot of fresh produce -- we pureed some veggies or fruit, and he stole snacks from trees and vines in the yard much of the year (figs, blackberries, apples, sour cherries, and guavas).
I would say his challenges early in life didn't impact him late in life....except: his cancer was that the bone cancer hit him EXACTLY where there had been a pano lesion on an xray as a pup. It could be coincidence, but...no one knows.
I was just talking to a vet I love about GSD cancer this week, and she said to look at Nutrocept:
The company has a parallel OTC product called EverPup that's about half the price. I'm not sure what the difference is. Their line is interesting because some of the ingredients are targeted to apoptosis (they also make Apocaps). The problem is the dang flax seed they use -- one of mine is allergic.
I also think environment matters for them, as for us. There are places in the U.S. where the expected lifespan for people
is much shorter than in other areas -- compare Louisiana and Colorado! I would bet the dogs follow the same regional patterns. I also think exercise and body mass for them over a lifetime probably matters just as it does for us. The obesity trend for pets likely carries some statistical risk of shortening life spans.