I was thinking to use birdshot or something a bit bigger in the house, I don't want to hurt a neighbor. I imagine a slug would go thru the walls
I only mentioned deer slugs due to recoil. You are correct they are not a good choice for home defense.
Everyone that shoots has has their theories about what to use for home defense that range from their misperceptions of what a jury might think to what would Rambo do. I prefer to go with scientific study.
"For personal defense and law enforcement applications, the International Wound Ballistics Association advocates number 1 buckshot as being superior to all other buckshot sizes.
Number 1 buck is the smallest diameter shot that reliably and consistently penetrates more than 12 inches of standard ordnance gelatin when fired at typical shotgun engagement distances. A standard 2 ¾-inch 12 gauge shotshell contains 16 pellets of #1 buck. The total combined cross sectional area of the 16 pellets is 1.13 square inches. Compared to the total combined cross sectional area of the nine pellets in a standard #00 (double-aught) buck shotshell (0.77 square inches), the # 1 buck shotshell has the capacity to produce over 30 percent more potentially effective wound trauma."
Use that as a starting point and research the topic. Science trumps Hollywood fantasy or 'Goober Gun talk' every time.