I love the Bobaverse Novels. They are not high art, but they have an enthusiasm for space exploration sci-fi that is catching.

When an author resumes a series after he's completed a trilogy, het tends to have a number of books planned out and in many cases this results in novels that are meant to be read sequentially and lack a clear ending.

I'm glad to say that Heaven's River is a standalone novel.
There is no reason to wait for the next few books to be out before reading it.