You can prevent your restaurant staff from navigating away from the Orders2me order receiving App on the Android tablet by enabling the Android "kiosk/pinning mode"
The steps can vary depending on the particular model and operating system version your tablet is running.
Here's a brief article from Google showing how to pin your app on the tablet screen: https://support.google.com/android/answer/9455138?hl=en
NOTE: The Kiosk Mode for Android requires;
- Android version 5.0 (Lollipop) or higher