An old monitor + previous generation Raspberry Pi: hangs on the kitchen wall to display Find My Friends in kiosk mode. Connected to a timer so it's on in the afternoon until dinner so you can see the family come home. Really cute to see your children move as little picture icons across the map towards you from school.
At what age do you disable the tracking? My parents' tracking of me in the 1990s was awful enough. I dread to think what they have set up I were 12 years old today.
That discussion has not come up yet. The kids are old enough to be able to switch it off themselves on their phone if they wanted to but so far they seem comfortable with it.
It works both ways: they can see at any moment in time where their parents are, which may be a soothing idea. With one parent travelling a lot for business the screen in the kitchen teaches them a bit about geography too. (What country is mummy in now?)