Unless you are planning 9mm or 300 blk, you are giving a clear indication you don't have much experience with "pistols" or SBR's..... but that's ok!
8" barrel in 9mm, no problem. 8" barrel in 300 blk, no problem... especially if subsonic & suppressed.
8" barrel in 5.56???? That will hurt even outside. Literary hurt. Even with earpro, the concussion will give you a headache... make your teeth hurt! Too short for all but the most expensive silencer.
If your idea of an 8" 5.56 for a compact home defence weapon, think again. The concussion from lighting that thing off inside will take you out. Not to mention loosing your night vision from the flash. It can actually cause an over pressure that can cause people to pass out... would suck if the blast knocked you out, but not the crew robbing your house. Wonder what they would do to wife and kids while you sleep? Who knows, maybe they will run away.
Pistol shines for in home self defence. Easy to keep it tight, easy to cut corners for clearing. Yea, it will be loud if you light it off, but it won't knock you out or blind you from muzzle flash. Plus its small enough to keep loaded and locked in a quick access mini-safe... got to keep it easy to get for you, not any kids.