This is a complex one. I'm almost certain the reason is they want to scan for bluetooth devices to pick up the vacuum cleaner in the app.
The problem is that scanning for bluetooth devices basically is GPS because marketers started putting beacons all over the place and using their tracking toolkits in apps to pick up these beacons.
So android changed the permissions so you had to ask for location access to scan for bluetooth.
So as an app dev, you get the option to ask for location access and make setup easy, or you can direct the user to go to the bluetooth settings and pair with the vacuum and come back to the app to continue.