There are also dog/cat tags you can implant and be scanned when crossing a threshold… in other words, I too see this as intrusive
Somewhere on the web I have seen a similar case and the person came reasonably far, I just cannot find it anymore.
I get the creep factor… My real life use case is we have an elderly family member living with we who tends to wander. I need to set up alerts for when she enters certain areas of the house (kitchen, shop, garage etc)