Yes, I worked with one that was doing millions in ARR

Also, a post a few minutes before yours is a bootstrapped B2B company, Zulip an open core Slack alternative

https://news.ycombinator.com/item?id=38659529

> Can you share strategies for AI (read: building and tuning models) startup to sell to B2B space?

This space is in hyper-hype mode right now. There are 100s if not 1000s of companies trying to do the same thing you are right now. Open source dominates the space outside of the big players like OpenAI, Google, and Microsoft. It's going to be really hard to differentiate, and no one knows where they will find applications with an ROI