I have a side project that aims to organize your ebook highlight collections with on-device semantic search. [1] Right now it only indexes your own content but I'd like to add a mode that allows you to share your collection and let others find relevant ideas via semantic search -- a discovery platform for ideas found in books. It's open source if you want a sense of how it works now. [2]
[1] https://emdash.ai/
[2] https://github.com/dmotz/emdash