That’s why I asked for your suggestions, to help me decide. I believe selection of the weapon and ammunition is the best way to reduce the threat to bystanders, except to decide when deadly force is necessary and hitting your target. My policy is to call 911 and stay put, unless it is to defend someone. That way you know where the intruder is, they don’t know where you are, and they are likely to get a nasty surprise. My house gun is a 16 gauge deer gun with #3 buck and the nearest house is 500 feet away, through the woods so I have little chance of hitting an innocent party.
I like your tagline.
My main concern is friendlies in the house, you need to be aware where they are. So for that reason, you may want to load down.
You may want to go to one of those mobile trailer enclosed ranges to get an idea, if you have never fired a gun inside an enclosed space. Most defense shootings take place at distances of less than 7 yards, according to those who study such things. Our local trainers say this and recommend that you use that range and focus on gun familiarity most. They also recommend pistols as the primary defense arm, which I adhere to. It's too easy to get a long gun taken away in a close encounter, so they say.
Number 3 buck or even #2 bird shot is still quite deadly at close range. Either would be fine for defense. I use a compact pocket-able pistol in 9 mm with Corbon defense loads. With the compact, you can pocket the pistol if need be, and see what the commotion is, of course, situation depending.
The call 911 route first is best ... if you have the time.
As they say with opinions, everyone has one, so practice and make your own choices are generally best.