I've recently built and application called "WallSync" that runs as a service using wallhaven api and automate your wallpaper transitions:
https://github.com/Gnyblast/WallSync
I recently came up to a point that I wanted to use a user's favorites collection but realized that search query through the website or API doesn't allow the feature to get the published collections of a user.
Is there any plan on adding search with favorites ID?