Probably not accurate anymore but they published a blog post about their first three months (it hasn't been a year yet!) after their official release. It was free during the beta before then.
Sure but sounds like they also had high churn (free and paid). Lots of people will give an interesting-sounding new product a try, but then bounce if it doesn't meet their expectations.
https://blog.kagi.com/status-update-first-three-months
Seems like they were at 2600 paid subscribers, but the wording indicates that they were seeing a pretty solid growth rate.