Interactive PDF indesign, one page visible at a time, pages hidden until corresponding button click

In Acrobat, you can use Page Templates to "hide" the pages. Then some simple JavaScript to show the page when a button is clicked. 

You probably want the button to be disabled after the page template is shown or multiple copies can be added. 

You can link your Interactive PDF to InDesign's Publish Online so that a button on the PDF launches separate Publish Online pages (and a button to take you back to the PDF).

instead of different pages, have only one page, and have all other pages in different layers that appear/disappear? its all show and hide buttons

It is possible but it will only work with "real" PDF reader software (Acrobat, Foxit, PDFStudio,…), it will not work with low-end PDF reader software installed by default on PCs and mobiles devices.

However, there is a way to prevent opening such a PDF in such software.

You can do that with JavaScript and Acrobat Pro but it's a bit technical, the easiest with InDesign is to transform each page into a layer and use the Show / Hide Layer function.

Maybe I've missed something here, but can't you just set it to export as a single page when you export it? While a user can still scroll technically, I suppose, still, a single page would appear at the time.

There are third-party apps which (at extra cost) that offer this facility, for example: https://www.paperturn.com

The answer is no from InDesign. You can check the Acrobat forum to see if there are some solutions available via Acrobat but they won't be honored in other PDF readers.