You are assuming the signal is strong enough to be read at a distance. I just used the RSSI, and going away a few meters was enough. Moreover, since that was just a nicety in case I forgot to lock my computer during a corridor conversation, I could get away with a longer timeout.

A more sophisticated implementation could be done if you can write software on the device. A PineTime would be perfect for this.

I am not sure why mention iOS specifically, a phone is easily forgettable. Moreover, you don't really need to rely on any location API provided by the system, even if UWB or Bluetooth Location Services would do wonders for this, a simple RTT latency measurement or RSSI value should be enough.

I always carry my phone, even if moving to another room. I assumed that a similar behavior is why you got rid of your wristband.

No, I got rid of it for multiple other reasons: started using a mechanical watch again, got rid of all proprietary software on my phone (though I used gadgetbridge for a while), realized anybody could just track me as the band was broadcasting the same MAC address everywhere.

I also got multiple LG watch R, I'm probably going to fiddle a bit with them when I have time, hopefully mainlining them and porting postmarketos over. I'm open to trying again with those. In the end, I don't really have sensitive documents on a laptop (besides work-related confidential stuff), so I'm not sure I'd crank paranoia to 11.

As for my phone, I often pull it out of my pocket and leave it on my desk, or abandon it somewhere, charging or powered off -- I should probably be more careful with that, but people know to expect some latency when contacting me.