if you're intent on a pepper spray for HD, consider pepper balls shot out of a paintball gun like a Tipmann TiPX or similar. It will localize the OC to mainly the target instead of like a grenade. Downside is the pepperballs are expensive. SALT pepperballs are about $50 for box of 10 with a 5 yr. shelf life per the maker. I bought a box of 500 paintballs to practice with instead of using the pepper ball for practice. If you buy the marker separately from the pepperballs it will be cheaper than the SALT kit. Check Amazon.
From your post, your home has stairs. To think out of the box, I would also consider a water gun or "tactical" spray bottle (kidding) filled with oil or soap to spray on the stairs if invaders approach. Also consider making caltrops aka metal kid's jacks to throw on the stairs to slow down invaders. Should be easy to cleanup afterwards. Like a home alone scenario, get some old alley 15-16 lb. bowling balls to roll down the stairs at invaders, but might damage stuff.
Although I got the pepperballs mainly to use in the open garage from an intruder prior to me utilizing more lethal protection, I prefer a handgun, pump shotgun or lever rifle in pistol caliber for HD.