The value of clay is is not its code base IMO. Clay connects many providers that each have licenses starting around $100-150/mo. Even if you open source your solution, users would still have to purchase subscriptions individually, manage their usage, etc. This can get expensive quickly. On top, it takes time and is annoying. Lastly, there's complexity to self-hosting the AI and web scraping stuff. I'm unsure if there are many GTM teams willing to put up with hosting this themselves.
Fun fact, you can actually rebuild the entire core functionality of clay using https://pipe0.com with ~1000 lines of code.