Usar la aplicación APKPure
Obtener Smart App Swicher versión histórica en Android
Una aplicación sencilla para la conmutación rápida entre otras aplicaciones.
A simple Application for fast switching between your favorite apps that you use frequently , similar to Omni Swipe (ex-Lazy Swipe) in switching between apps except that you choose the apps you want to favorite your self and it works as floating widget similar to facebook messenger chat head.
You can check the linked video to see how it works.