In a couple of related topics linked below, it has been mentioned that there is an old, non-configurable slideshow functionality that can be applied to projects, by adding /stats_slideshow to the end of any project URL.
Otherwise no more general slideshow functionality currently exists, and I think would be much welcomed if you wanted to give it a try. I may be wrong, but I get the sense current staff don’t have much appetite for developing this, with everything else on their plates.
https://forum.inaturalist.org/t/presenting-a-project-as-a-slide-show/7968
https://forum.inaturalist.org/t/present-data-in-full-screen-slideshow/3289