Found this on github.com with barely 400 stars, which is criminal. You feed it a guest name and a topic; it returns a research dossier: past interviews, recurring stories, contrarian takes, and draft questions that avoid what every other host already asked.
Setup is one git clone and an API key. I used it for two real interviews this month and both guests commented on the prep.
The takeaway: Great podcast prep is a research problem, and research problems are now automatable.