Is there any example on how to use this library against OpenSearch?

[DumboJet]

I want to load an NHibernate entity from a DB, push it to an OpenSearch node for indexing, and then query OpenSearch using C# expressions.
Is that possible, and are there any examples for that (mainly the OpenSearch part)?
I was looking at the tests and I was hoping it would be something like this, but there is an apparent problem: I have not specified the OpenSearch Url anywhere (nhSession is the session towards the DB):

                IFullTextSession s = Search.CreateFullTextSession(nhSession); // nhSession is the session towards the DB.
                using (ITransaction tx = s.BeginTransaction())
                {
                    s.Save(doc);
                    tx.Commit();

                    var res = s.Query<Document>()
                        .Where(f => f.CreatedDate > DateTime.Parse("2023-08-01"))
                        .ToArray();
                }

Is it possible to get an ISession that points to an OpenSearch node or cluster, instead of a relational DB?
It would be nice to have some sample code in the README page.

Also, what I am trying to do when querying requires building complex filter conditions, unlike the examples here, so that's why I was wondering if I could use expressions, similar to what is shown for the Java version here.