You can initially add photos to your Nixplay app without opening it through this shortcut.
See the steps below along with photos for reference:
1. Select the Photos app 
. Tap on the photos you want and hit the share icon in the left bottom corner.
2. Select the Nixplay icon from the sliding up panel
*If you cannot find the icon, try to go to “More“ to find the Nixplay app in the rest of your list.
3. You can choose to add captions by tapping on the empty space below each photo and typing your preferred captions or text to appear with the photos when shown in the frame. Then hit Next.
4. Select your preferred playlist or friend then tap on Send.
