From what I can tell, PathQuery is also clever in how queries express the shape of the returned data, which we in GROQ call projection. For example, in GROQ you can do:

  *[type == "user"] {
    id, name,
    "slug": id + "-" + lower(name),
    "photos": photos[] {
      url, width, height
    } | order(position),
    "newestComment": *[_type == "comment" && author == ^.id] | order(createdAt desc)[0] {
      id, body
    }
  }

PathQuery seems to give you similar tools in transforming data as part of your pipeline, which I think is how query languages should be like.