I believe I have access to troves that have never and will never be online. Some quick research has not turned up any obvious marketplace online or who to talk to.
Is anyone here in this business or have any advice or resources for people like me who want to explore offering training data for sale or license?
Cloudflare's new marketplace lets websites charge AI bots for scraping
And make sure you're confident about the value. For example, in many workflows having only 10% coverage of the population makes the data useless.
I wouldn't worry about the licensing details as a startup. It won't matter until you can afford lawyers and reputational damage for pursuing someone who's broken the license.