Ask HN: Is there a good internal search product?

A lot of friends indicate to me that the organizations they work at have siloed sources of data and often find it difficult to find the specific information they're looking for internally.

My friends at VMware, for example, often use Google search to find their own documentation. Is there a service that provides integrations and a search tool, and perhaps even a virtual assistant for enterprise? I imagine the work is fairly scoped down as compared to general usecases and something impressive could be built.

I'm aware of tools like butter.ai, but they were acquired.