It looks like all the academic literature for peaches and a lot of other fruit says that post bloom they can survive down to 28 degrees with minimal damage.
What happens when the fruit gets bigger than just post boom/fruitlet - say marble or golf ball size. In your experience are they still able to withstand down to 28/29, or will 31/32 degrees burst the cell walls and destroy the fruit?
Mine ended up just turning brown and dying when we had a freeze. I saved most of mine with sheets covering most of the branches. That has been my experience in my area. Perhaps others have had better luck or a difference experience with this than I have had. My peach trees have only been producing for two years now. That has been my experience.
Freezing or just below doesn’t normally damage blossoms or fruit. But it gets complicated later in the season. Once the tree has significant leaves that can protect the lower fruit. Then to it’s very hard to measure temperature within a couple of degrees. Once fruit has formed I’d be very concerned about 28 for very long at all. I’ve not seen much damage at 30 at any stage.
There are fruits that are damaged at 32. Namely grapes, persimmon, figs, and other similar heat loving fruits that are very low chill. They don’t like freezing at all. The foliage can be even more sensitive than the fruit. 32 can make a mess out of grapes and the like.