On UWP this can be achieved if you set double.NaN as a value of the DrawerLength property and on Android this achieved by setting 0 as a value of the DrawerLength property. On iOS is not supported at all.

When using a AreGesturesEnabled = true, stop the length of the drawer at location of releasing the Gesture.
Then allow the user to cover the drawer with the entire screen.

I would like to have an offset property for when the drawer is closed. The reason for this is we want to have a mapview with an expandable drawer at the bottom, but when it is "closed" it is still partially visible in order to have a less detailed version of the information that is inside the "opened" version of the drawer.