There's a good overview of Brave's search engine focus from their team (the former Cliqz team) found in https://www.theregister.com/2021/03/03/brave_buys_a_search_e...

Paper on the search engine: https://drive.google.com/file/d/1-B3ZvHpbnxsT2OdnUH8vS3-tvTv...