The URL Launcher is a pre-installed app which will load the Today+ if the Today+ URL is set in the "Set URL" menu. The LG Kiosk Mode is also a pre-installed app which will disable any attempt of closing or exciting the specified content. Touch can still be enabled while Kiosk Mode is running and Kiosk Mode can be disabled by performing this gesture.
To do this open the LGKioskMode app → Make sure that the URL Loader is selected as the Default App → Enable Touch Mode → Insert the Today+ URL in the Set URL field → Finish by pressing Reboot
After rebooting the LG Screen will run the URL in full-screen mode. To exit the full-screen mode, turn the tablet vertically and slide your finger in the "L" shape shown below: