Nested Carousel where users can create a unique template such as the nested slider which currently exists in bricks
My definitions of slider VS carousel might be outdated but… If you set the slider to show 3 slides or whichever number you want, add a gap, decide how many cards/slides to show/move on pagination or arrow click… Isn’t that pretty much a carousel?
The splide slider is extremely versatile especially once you get into custom options n stuff. What exactly are you looking to build that you currently can’t?
The slider slide all 3 pannels at the same time… I would like it to just move one at a time. But from what I see its not possible.
It is with the per move setting 
it’s natively available in bricks but just as a quick example, here it is shown in the splide docs Options - Splide