With Telerik Popup for Xamarin you could easily add modal popups to your application in order to draw attention to important information or receive user input.
RadPopup lets you display content of your choice on top of existing view. The component provides a flexible API to easily control its behavior and makes possible the implementation of complex logic for a wide range of scenarios.
Modal popups: You could define whether the popup will be modal or not; in both cases the UI behind the popup gets inactive and cannot be used until the popup is closed. When you have a modal popup, it will not be automatically closed when the user clicks outside. For more details go to Modal Popup Support.
Placement configuration: You could place the popup control at any position through various settings such as placement mode, placement target and horizontal/vertical offsets. For more information on this check Key Features: Placement Configuration section.
Animation settings: RadPopup provides sleek customizable animation played while the control is displayed/hidden, for additional info go to Key Features: Animation Settings.
Check out RadPopup Getting Started help article that shows how to use it in a basic scenario.