I really like this approach. I worked on this problem (create a nice background for an image) for a couple weeks many years ago while organizing my desktop wallpaper collection, and never came up with a good answer. Unfortunately, I think that it's been "solved" in the tiktok era; an enlarged and blurred version of the image is used to fill the background space.

The blurred mirror is inoffensive to almost everyone, and yet it always strikes me as gauche. Easy to ignore and yet I feel that it adds a lot of useless visual noise.