This is an interesting idea because this particular URL is not just an image, but a full on webpage. I think this could work if we add this in an
We will definitely add new ways to add backgrounds in the next major update, and pasting a URL will be one them. This is on the roadmap, but no idea when we'll start working on it !
Currently, we can only choose between unsplash and local file. How about ability to set background from URL?
For example: https://live2d-dcg.github.io/viewerK.html?mN=c342_10&size=700&mS=1&mX=0&mY=0