In my demo you can check the behavior of "Digi Showcase - Carousel horizontal with 3 items" module. It has 3 slides from desktop and from mobile. It's exactly your scenario. If you need a scroller with 3 columns on desktop and only 1 on mobile, this module cannot help you. I'm sorry.
Besides you can consider to create two modules, one for desktop and one for mobile and then hide desktop one on mobile devices and mobile one on desktop devices. It's not a "very clean patch" but it could work.
You are welcome, hope you can solve that and use Digi Showcase.
If maybe you like that module and you are willing to spend 3 minutes of your time, a review on Joomla Extensions Directory would be really appreciated.