Hang on Duncan. So you have a dog... and presumably buy dog food about weekly. And you always buy the same brand.I have had this happen to me many times.
I once said to my wife "we need to get dog food." The phone was on the coffee table. Later that morning when I went on the internet the first advert that popped up was the exact brand of food we buy.
We always did the shopping online. So they took the verbal data and matched it to our search history data. So yes they certainly are listening.
They even have a term for this type of data collection - SURVEILLANCE CAPITALISM.
I'd be more suspicious of your credit card, the receipts from the online shopping. Etc. You could not even have a phone and it would be easy to identify your buying habits.
Isn't it better that you get ads for specials on your favourite dog food than say budgie food anyway?