To insert an Elementor page into a GP Section, create your Elementor content and save it as an Elementor template (if you have Elementor Pro). If you do not have Elementor Pro, the use the free version of AnyWhere Elementor to do the same thing. Each of these will generate a shortcode that you can then insert into a GP Section.
Just a few minutes ago I found “Insert Page” plugin. It also can do this job but I prefer your solution. “Anywhere Elementor” plugin mantain clearest the page list.