I don't believe there's a node package but you can call the Search & Navigation service directly by passing in the key so you can create your own HTTP requests directly to your index. If you need to know what to call do something in a C# example and look at the outgoing requests to the index.

For example the call for autocomplete is https://usea02.find.episerver.net/KEY/INDEX/_autocomplete?prefix=test&size=10 with the key and index being your values. So you can make direct calls you just need to handle the serialization yourself and figure out the HTTP request structure

Also I've deleted your old duplicate post