So it's not a search engine, it's a frontend for a search engine.
It’s possibly worth pointing out that the about page doesn’t offer any indicator that this is an actual nonprofit entity from a legal standpoint, so at this point I have to assume it’s just a sole proprietorship that is pinky promising to become a non-profit.
In that sense I’m quite happy “donating” to Kagi to provide a stable and supported product from a company with employees.