Thanks for sharing the details & the shortcut. Even better that it can be applied to any wallpaper as I was expecting that the shading effect was manually applied to the wallpaper.
I tried opening the shortcut but it opens the shortcuts app shows a dialogue box with progress wheel and then crashes to home screen every time. I am still on iPadOS 13 so this may be why? I will be interested to hear if anyone else can get it to work?
Thanks!
P.S. I just checked the Homescreen Creator website and it is indeed for iOS 14.3+
P.P.S. On further inspection of the website it says iPhone only.