I'm doubtful one exists for android or iOS but I can imagine it wouldn't be that hard to implement with a smartwatch signalling to a phone (instead of a laptop)

I'm doubtful one exists for android or iOS but I can imagine it wouldn't be that hard to implement with a smartwatch signalling to a phone (instead of a laptop). The only trouble a developer would have with implementing is if they have sufficient access to APIs that might be private and the ability to run a background service using the APIs at a sufficient interval.