Conflict when simultaneously using keyboard events for scrolling and CSS scroll snapping

I guess there is not, the css overwrites the javascript. But you can simply add wheel eventlistener like:

window.addEventListener("wheel", function() {
    if(event.deltaY > 0){
      animate({
        easing: "out-quintic",
        change: animateScroll(1)
      })      
    }
      if(event.deltaY < 0){
      animate({
        easing: "out-quintic",
        change: animateScroll(-1)
      })      
    }      
});

https://codepen.io/kostjaaa/pen/NWWVBKd