Great question. We didn't go into too much detail, but we've built a conceptual search index which maps all these disparate items into vectors that are then used for searching, similarity, ranking, etc. Here's a talk by me from a while ago about an earlier version of the system: https://www.youtube.com/watch?v=J4O42EWfHoo&t=5s

We can go more in depth on the current version of our system if you think that'd be interesting!