they would have to constantly check an app

need the victim to monitor their own stalker

neither of these are true. moth understands, sometimes it is easier to see a headline and jump to conclusions. but when you do that, you form opinions that are uninformed and incorrect.

the monitoring is done by the authorities, and the victim is notified only when the stalker is within 2km of them. at 1km range, the police are notified and dispatched, and the probation officer calls the victim to talk them through the event.