In case you're interested in any of the abstract backgrounds you see on recent iPads and iPad Pros, you can get desktop versions of them here (https://drive.google.com/drive/folders/1bL1ks2wGeg_gxypDFbc0PwkQ-ht4DvZR). Some of them are quite well done. I currently have a bluish one as my desktop picture in Ubuntu. Check them out. When I was looking for these, I also ran into a site that had desktop versions of the Samsung tablets, but I didn't record the url. I'm sure you can find these easily if you're interested.