My brother in law flew from San Francisco to Toronto for Christmas. Did his quarantine at an Airbnb. He's heavily into tech (MSc from MIT in computer science) and took a long look at the app. He said that the quarantine app tracked his location through the phone (he didn't leave the condo for 15 days). No knocks but did get phonecalls. Everyone else I know has had knocks as far as I know.
I suspect that if it does track your phone and you were shown to have movement you would get a knock...
your phone tracks you for google or apple within 5 feet of where you have your phone.
I have misplaced my phone more often then not, and the track my phone feature even tells me that my phone might be on the second floor of a two story building.