Yes, but not fully. They have their own index as well. They have also recently started a partnership with Ecosia to focus more on that effort.

FYI: Kagi uses the Russian search engine Yandex as well and have no plans of changing it.

Mentioning it, as to some it might be an issue indirectly financially supporting a Russian company.

Just search for Kagi Yandex and you will get plenty officiak sources