The M400 and M4000 can run most any Android application compiled for a minimum SDK version of 27*. Because of this, deploying applications to the M400 and M4000 is often as simple as updating your existing application to allow button navigation.
Most Android developers prefer Android Studio. You may use any Android development environment including Android Studio, Xamarin, Eclipse, IntelliJ IDEA, and many more.
To get started, simply create a new Android project with minimum SDK version 27*.
*Targeting a minimum SDK version of 28 is an option if you only plan to support M400/M4000s running OS version 2.0.0 or later.