There's an application on Google Play that allows you to find out if your Android phone / tablet is supported by Delphi XE5.
It's called Delphi Support. If it shows up for your device, when you use Google Play, your device might be supported. In order to know for sure, you need to install and run the application.
If it doesn't show up for your device, it definitely is not supported.
In 2017, with the release of Delphi 10.2 Tokyo, Embarcadero introduced a specialized implementation of the Observer pattern into the System.Classes unit. While it has been in the wild for 9 years, it remains a "hidden" architecture for many, primarily because it serves as the invisible engine behind LiveBindings. Other than live bindings, you can also use the Observer pattern as a way to update component settings to the Windows registry, an .ini file, or persist it elsewhere.
System.Classes