Updated and Modified for Nativescript Core 7

Steps to create an Android App Widget in NativeScript

Create an android layout for your widget and place it in platforms/android/src/main/res/layout. Make sure to follow the official guidelines as not all views are supported.
Create a widget meta-data file and place it in app/App_Resources/Android/xml/.
Extend android.appwidget.AppWidgetProvider and implement its onUpdate method. For more information on how to do it refer to the Android API Guides.
Update the AndroidManifest.xml located in app/App_Resources/Android and register your widget, where receiver android:name=??? contains the full widget class name, and meta-data android:resource=@xml/??? - your widget meta-data.

Note: A full widget class name is only considered valid when it contains package descriptor eg. com.tns or a.b in the front.

Added resolve(__dirname, "app/myWidgetClass.js") into webpack.config.js under appComponents

tns run android

Add the widget from the application WidgetDemo to your home screen.
Clicking on the button on the right will increase the tap counter, while clicking on the image will open the application with which the widget is associated.