A loop or a trip between two points, the length, the effort and what you like to see: Vistavel composes several routes and traces each on ways suited to bikes.
Yes, as GPX: Garmin Connect, Wahoo, Komoot, Strava and most apps import it. The file carries the route name and the vistavel.com signature.
Where does the data come from?
From OpenStreetMap contributors and a bike router. Routes are composed automatically: check the state of the ways on site and follow the rules of the road.