It is was me I would likely build something myself using jQuery and AJAX and either have a button to show more or build my own infinite scroll for it. I don’t have any examples or I would share them. I don’t generally work with gallery fields and there are several pieces that all need to work together to build something, probably would be a couple of hours work.
I do have an old example of a load more for a repeater that uses a button https://github.com/Hube2/acf-dynamic-ajax-select-example/tree/master/repeater-ajax-load-more, the principle is the same. The only difference with infinite scroll is that you need to detect when the page is scrolled far enough to trigger the request instead of using the link.
Don’t thank me for the plugin, I’m just another developer like you that uses ACF for nearly everything I do and I could not do what I do without it either.
