Pummeling Style + Sunder Combat Maneuver

Looks to me like you can use both. Totaling the Damage from Pummeling Style to the amount of Sunder damage you do to the Weapon/Armor/other item.
Take the Brawler Archetype, Steel Breaker, and you have a bunch of naked/broken mooks.

Interesting.

Martial Artist monk can use it that way too. The problem is, steel breaker and martial artist don't need pummeling style to break weapons and armor, as sense weakness already allows them to ignore hardness.

Absolutely. You can substitute out a Disarm, Trip, or Sunder for any Melee attack. With a Flurry you can do a bunch of sunders in a row if you like.

This makes me look over the Snakebiter and Strangler Archetypes for the Brawler... and damn; those are nice!

Martial Artist monk can use it that way too. The problem is, steel breaker and martial artist don't need pummeling style to break weapons and armor, as sense weakness already allows them to ignore hardness.

I just like the Idea that at 8th level I can Sunder Pummeling Charge, "Dusting" Armor and Weapons with a Single Punch.