I don’t know about federated, but there is SearXNG, which is FOSS. There are public 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 public 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.