[elrostelperien]

For macOS, there's this: https://pdfsearch.app/

Without AI, but searching the PDF content, I use Recoll (https://www.recoll.org/) or ripgrep-all (https://github.com/phiresky/ripgrep-all)

[gumboshoes]

The best indexer for macOS, bar none is Foxtrot Professional. https://foxtrot-search.com/foxtrot-professional.html Very sophisticated searching, including regex, its own query language, and proximity searches - x within z words of y - which for me is the biggest win. I have 2TB of files indexed with this.