We should consider exposing a property that will leave the side drawer opened even when you click on the main content. 

Currently only Views can be hosted in the MainContent. If users can host Pages the RadSideDrawer could be used as root navigation component. This will allow customers to define the RadSideDrawer once throughout the application.

A few things are missing from Xamarin RadSideDrawer. Here's some we found in Android docs, unavailable on Xamarin Forms (and currently causing us issues that require rethinking the app's workflow, as we really needed a drawer that stays fully locked and cannot be dismissed by the user).

 

drawer.TapOutsideToClose
drawer.CloseOnBackPress
drawer.IsLocked 

Sets the number of pixels from the screen edges that will define the touchable area which allows to open the DrawerContent

The property is available in native controls:

Android: TouchTargetThreshold
iOS: EdgeSwipeTreshold
UWP: TouchTargetThreshold

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.

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.