Based on the documentation the origin
parameter is optional and it defaults to the user's location.
... Defaults to most relevant starting location, such as user location, if available. If none, the resulting map may provide a blank form to allow a user to enter the origin....
ex: https://www.google.com/maps/dir/?api=1&destination=Pike+Place+Market+Seattle+WA&travelmode=bicycling
For me this works on Desktop, IOS and Android.