Can I make the mocked point perfectly steady or, on the contrary, more lifelike?

“Perfect accuracy” keeps the point still and moves it along a route exactly on the line — handy for testing geofences, trackers and automated tests. “Like a real GPS” is the default: slight jitter and a lively heading, like a phone in your hand. “Weak signal” increases the jitter and the drift from the line, like among tall buildings. “Battery saver” sends the point once a second instead of four times.

You can set manually the point jitter in place, the reported accuracy (better than 2.5 m — it cannot be worse, otherwise Google services may mix in your real location), a custom altitude above sea level, the drift from the route line, the heading jitter and the update rate. Under each option it says what other apps will see. Without Premium the “Like a real GPS” default applies; your chosen settings are kept and come back with the subscription. Details are in the guide on GPS realism.