On my Samsung Android phone, I do this...
- Add App XYZ to App Lock (AL) list
- Turn Off WiFi
- Select App XYZ
- See AL ask for pin
- Tap the 'o' from " o ¥ at bottom of screen
- View 'reduced' image of App XYZ in all its glory.
Clearly App Lock has NOT prevented me seeing the 'locked' App. This might be a secure messaging app like WhatsApp or Signal, and so reveal groups I use.