Take a look here https://github.com/marqo-ai/local-image-search-demo. It is based on https://github.com/marqo-ai/marqo. We do a lot of image search applications. Feel free to reach out if you have other questions (email in profile).
I also researched in the meantime whether such a functionality could be implemented at all for the Gnome Shell and, more specifically, for its file browser. But the search and extension APIs would not even allow it or require many hacks.