I don’t know about federated, but there is SearXNG, which is FOSS. There are plenty of public instances or you can run your own instance.
If you are willing to pay money ($5-10 USD) then I recommend Kagi. In my opinion Kagi is worth the money, as it it provides much better results and has a lot more features. Like SearXNG, it is also ad-free.
Whats a good federated search engine?
I know peertube has: https://sepiasearch.org/
I don’t know about federated, but there is SearXNG, which is FOSS. There are plenty of public instances or you can run your own instance.
If you are willing to pay money ($5-10 USD) then I recommend Kagi. In my opinion Kagi is worth the money, as it it provides much better results and has a lot more features. Like SearXNG, it is also ad-free.