I've reached out to find out more about Glean.
Having a look through Danswer's docs and videos, it seems more like search for documents, then selectively pull them into the context window for an LLM chat interface, which isn't quite what I'm looking for.
I want someone out of core timezone to be able to find useful answers to questions based on Slack/Confluence/Basecamp/Gitlab/GDrive content without having to wait for the Product owner to wake up the next day. Or if there's a question from a customer it can be answered in context with that customer's account information and deployments without having to find the specific team member who usually works with them.
I'm currently trialling
https://www.eesel.ai/ locally, and it's really good at remembering where I saw something as a browser plugin. I might try their larger deployment next.