Why Google Maps does not export GPX directly
Google Maps is good for planning directions, but it does not provide a direct GPX export for GPS devices.
Google Maps is not a GPX editor
Google Maps is designed around directions, live navigation, and place search. GPX is a file format used by many GPS devices and route-planning tools.
Because Google Maps does not offer a direct GPX export, users often need a converter between a Google Maps directions URL and a GPX file.
Why conversion can vary
A directions URL can include place names, coordinates, waypoints, and internal route data. The more precise the URL, the better the conversion result.
If only place names are available, the route may be recalculated and can differ from the route you saw in Google Maps.