Yes, puppeteer and ferret use same technology under the hood - Chrome DevTools Protocol.
But, the purpose of the project is not to "be better than". No, the purpose is to let developers focus on the data itself, without dealing with technical details of underlying technologies.
You can treat it as a higher abstraction on top of puppeteer / CDP.
It does not really matter whether it's written in JS or Go. main goal is to simplify data scraping and make it more declarative (even though, some people say it's not a declarative language :))
I feel in this case, it's solely to stay within a Go ecosystem which seems to be counter to what matters, business value.