It is not possible to capture location without a data change.
It is not possible to get the location of some other device: you can’t reach out to another user’s device and request the location. But if the other user’s device captures and saves its location to a table you also have access to, you can see that. It’s not real-time, but it’s the best you can do.
It is possible to map collected location data from other sources on a single map: if all devices record their locations to the same table, you can map the entire table.