pf2e.fyi
From Pathfinder Guns & Gears, which isn't enabled.

Explosive Expert

FEAT 13
Prerequisites Explosive Savant

Access You are from Dongun Hold or Alkenstar.

Through your extensive training with volatile weapons, you've built up a fair bit of tolerance to your own black powder explosions. You are immune to splash damage caused by your own Strikes with bombs and firearms (such as the splash damage from the scatter trait).

Pathfinder Guns & GearsORC