I would leave the phone and tablet and get a cheap one instead. They can access the devices location and if they are the bill payer they cut the contract off to try to get you to return.
I’m unsure about the rest but I know that women had issues with phones and devices being tracked and controlled and it caused a lot of stress. Some devices they could also access to try contact the child to ask them questions like where they are , I’m not computer savvy so i dont know how but I’ve seen it be done.