Reload a React Native app on an Android device manually via command line

Using the cmd line you can send a command to the Android device.

adb shell input text "RR"

This command tells the Android device to type the character "R" twice which is the React Native command to Reload on Android.

The adb shell command has many useful features many of which are described here:

ADB Shell Input Events

To open the developer menu:

adb shell input keyevent 82