Joe, revolvers can be left loaded without any adverse reactions, like to a compressed spring in a mag of a semi auto or a tube of a shotgun.
JJL recommended the CZ PO1. That gun is based on the original CZ75 which was the 1st! double action hicap 9mm in the world. A very good design and reliable pistol.
Joe, I keep a small .410 shotgun in my pants draw. A Snake Charmer I think it is called. I tried this out in the field, with 2 layers of 1/2" sheet rock and insulation in between. I fired at 20 yards with #6 shot and none penetrated the second layer of rock. Who is on the other side of that wall is of great concern. The .410 is my choice for home defense.
If you are set on a handgun, then by all means I would stay with the name brands( Smith, Beretta, Sig,Colt, Glock) and lean towards .45acp. More one shot stops than ANY caliber.