Hacker News Reader

It's only as good as the HN team have configured the ranking and other algolia settings. Be nice for them to expose these.

Pretty sure HN's search is implemented by Algolia themselves. It's served from algolia.com.

Correct, and the source code is here: https://github.com/algolia/hn-search

You cant self host algolia

No, that wasn't my point. You can't host the service, but you can self-host a site that uses it behind the scenes.