The main use for AI that I've seen in my circles is a search engine replacement. Not because AI is a good search engine, but because search engines have largely become useless.
If Mozilla wants to cement their place, create a better search engine. It's how Google came to control a huge portion of the internet, and there's now a huge vacuum waiting for someone to replace what we lost.
Oh, I'm sure that will remain true for at least three minutes after people start using them.