Show app above the lockscreen (i.e. Google Maps)
There might be a better solution out there, but for now this might help.



You can use screen pinning option.

Instructions to pin an app on the screen:


Go to Settings &rarr;Security&rarr;Screen pinning
Enable screen pinning and also the option "Ask for unlock pattern before unpinning"
Now open the app you want, then switch over to the overview menu
Tap on the pin icon on the app.


You are good to go!



To get out from pinned screen, hold Back and overview button at the same time.

By doing this you get to interact with the app without unlocking the screen, and also as an additional benefit the unpinning gesture helps you from accidentally exiting from the app!