I am pleased to announce that I have created (Thanks to the code of @Salman_Dev published in Wallpaper Manager problem? - Extension Development - MIT App Inventor Community) an extension that allows you to change the wallpaper of your mobile phone.
You can choose to change the home wallpaper, the lock wallpaper or both at the same time.
The extension consists of 3 blocks:
to set the wallpaper only on the lock screen.
to set the wallpaper in the home screen.
to put the wallpaper on both screens at the same time.
for the proper functioning of the extension it is recommended to request the SET_WALLPAPER permission
com.meulencv.WallPaperChanger.aix (5.8 KB)