I carry a Kel-Tec P32 as a shove in my pants pocket gun.
I use it mainly to shoot raccoons who get into the outbuildings and it works just fine and kills the raccoons, one skunk, and one coyote dead, dead, dead.
As for penetration, .32 fmj will actually outpenetrate .380 fmj and I have been loading Silvertip hollowpoints in my gun since I don't like putting extra holes in the walls of the buildings.
I have no issues using full metal jacket ammo for defense, especially in the winter.
.32 acp ball will get through heavy clothes and tickle somebodies innards and most of the time that is all it takes to vent the sap and wind right out of an adversary.
Is it my first and primary choice as a defense cartridge, nope, but I don't feel naked when I have my Kel-Tec in my pocket.
Having a gun, any gun, when one needs a gun, is far better than not having any gun and needing a gun.