Answers for "android install from apk file"

How do I get an apk file from an Android device

adb shell pm list packages
adb shell pm path com.example.someapp
adb pull /data/app/com.example.someapp-2.apk path/to/desired/destination

install apk using command

adb install -r <app path>
example: 
adb install -r ../android/app/build/output/app.apk
The -r flag is to replace the existing application.