I see 5 choices for search engine in Settings? Are you saying you want one not listed?

yes, for example they have Ecosia but not Qwant (they are said to share their index but for my searches, I often flip over to Qwant when Ecosia results for the same query are not adequate.) I understand why Safari went with a search engine whitelist but I wish there was a way to make exceptions.

Yes. The obvious choice for HN is not listed in it. It’s a silly limitation anyway.