I was aware of most of those items. I think that it is a good idea to keep any and all medications, even those prescribed for your dog, in a safe place. This way you don't have to risk accidental ingestion.
Xylitol may be the most common item to find in your household. Does everyone realize how many things contain Xylitol nowadays (at least in American products)? Chewing gum, mouthwash, tooth paste, hard candies, cookies, etc. Many mass producers are adding it as an alternative to sugar. My dog has a habit of picking things up off the floor and eating them. When I learned about the Xylitol issue a year ago, I went through the house and I replaced every item that contained it. It is supposed to be highly toxic with most dogs dying from ingestion. I didn't want to risk it.
I want to speak to the issue of avocados. Years ago, I had a situation where the family dogs were at my house because of a family get together. When the party was over, I found several pieces of fruit skin all over one part of the yard. It took me awhile to realize it was avocado. I thought they had gotten one of the avocados from our tree, but they turned out to be the smaller, soft skinned variety from our neighbor's tree.
I immediately called the animal emergency hospital. I had seen in my dog emergency guide that ingesting whole avocados could cause a problem. They researched it and called me back with their results. I was only to worry if a) it was the Guatemalan variety that was toxic (not the Mexican or Hawaiian) or b) they ingested the seed which could get lodged in their digestive tract.
They told me to keep watch on the dogs for the next 72 hours (which is how long a blockage would take to show). All the dogs ended up to be fine. No one had complications. It turns out they might not have eaten that much despite the mess. What I realized the next day was that the crows had been picking avocados off the neighbor's tree. They would sit up on the telephone poles and wires and eat them. When one dropped, they left it and got another. I suspect they had dropped a couple of these very small ones in the yard. I am sure the dogs got some, but most likely not much. It was a scary and stressful week, to say the least!