My children are using Xplora smart watches. There is an Xplora app through which it is possible to see the GPS location. There seems to be an unofficial API to get watch location etc. (GitHub - Ludy87/pyxplora_api: Unofficial python library for the Xplora® API). Any chance that this could be used with SmartThings?
That is, using Xplora watches similarly to a mobile phone as a presence sensor.