Microsoft have updated the Android version of Cortana to version 2.5.0 (Beta). The new version has the ability to add Cortana to the Android lock screen making it really easy to access the service. After updating and giving Cortana permission to access the lock screen and you will see the Cortana logo on the Android lock screen where you can swipe to bring up the Cortana screen. You can’t access voice commands from the lock screen but you can view your calendar and see your news feed.
The app is available in the Google Play Store.