Not sure, I don't grow peaches other than two backyard trees so I'm not very familiar with all the pest and defect issues. The brown spots could simply be blemishes from rubbing against adjacent branches, cosmetic only. It might also be damage from late season frost on the peach bud which can create necrotic patches. Or maybe corneum blight, a type of fungus. The tiny holes are likely an insect sting where they lay an egg or eggs, possibly a borer, paper wasp or earwig. It may be localized damage so you can still use most of the fruit.

Peaches in CO don't usually require much pesticide control beyond the early spring tree oil spray which can smother eggs and larvae preventing further issues. Growers here also spray the bottom 2 ft. of trunk twice in summer to control peach twig borer, crown borer and earwigs. Any of those could cause stings in the fruit.

A very wet year can cause aphid outbreaks, a very dry year can produce mite problems. If detected try to deal with them early because they can sap growth from the tree.