The phone has a GPS sensor and the OS can read the values from this sensor. Thus, the OS knows your real position.
However, the apps have no access to the direct OS reading - they can only ask the OS to give them the position. And the OS has builtin support to give them fake results.
To do that, do the following steps:
Enable developer mode (as described ...
It does not take into account your walking speed but assumes a normal walking speed. From Google Maps help
What is the Google Map walking speed? Is this a constant value or does it change depending on slope?
Normal walking speed is about 3 miles per hour - It does not adjust for distance travelled, nor for whether you are on a road or footpath.
It does ...