This will be a very simple job for a person who knows how and would more than likely take 5 minuets.
Basically i have a gallery plugin (its a free one) it works smoothly for my website (both pc/phone) but the issue is the rendering for Facebook instant articles.
Now Facebook instant articles allow you to submit Custom transformer rules so all it would entail is making a Custom transformer rule so it renders correctly to show the slideshow correctly on the Facebook instant article.
The plugin in question for the gallery is: http://foo.gallery/
If you know what you are doing and want to make a quick 50 bucks get in touch 🙂