The problem is that enthusiast gun owners don't want to be able to deter intruders, they want to be able to stop gun-owning intruders from getting off their first shot, in the hypothetical that the resident can surprise the invader.

In discussions, 45ACP is thus favored for 'stopping power' versus the smaller 9mm. The gun-enthusiast response to the penetration concern is either to ignore it and emphasize aim & intelligent planning, or to create expensive 45ACP 'frangible rounds' that shatter into a granular powder on impact. There also exist somewhat anomalous theories about buckshot/birdshot being safer.

The most common guns, though, are lightweight, low-recoil 22LR-caliber pistols that lower the kill probability significantly over any of the more serious pistol rounds.

One can certainly create less-lethal loadings, either with traditional lead or something else like rocksalt shotshells, but things that can penetrate a chest cavity tend to be able to penetrate drywall.

I'd just go with a Taser and pepper spray if I was concerned about the small chance that penetrative shrapnel ends up energetic enough to hurt a loved one.