As far as I know, even the lowest level permission has "create" rights on insights. What I do when I have someone in this type of situation, I create a board, make it "public", assign a password to it, and then give them that public board link with the pw (so that it's not really "public"). They can view the board with the included insights. They can't change them in any way, but can interact like scrolling if there are more elements than displaying in the view.