You can add two apps' shortcuts on the Galaxy S7's lock screen, which by default are assigned to Phone and Camera. To change lock screen app shortcuts on Galaxy S7 (Edge), do as follows:
1. Open the Settings app on your Galaxy S7 Edge or S7
2. Scroll down to the Personal settings and tap to open the Lock Screen and Security settings
3. Under the Lock Screen settings, tap the Info and App Shortcuts option
4. Now tap the App Shortcuts option, to specify a new apps for the Left Shortcut and Right Shortcut. Simply tap on it and then specify the new app from the thumbnail list.
Note that, if you want to remove app shortcuts on the Galaxy S7's lock screen, tap the left Shortcut and then toggle it OFF, and then do it for the Right Shortcut as well.