And I would get rid of the mouse events in favor of pointer events.

https://utilitybend.com/blog/the-customizable-select-part-on...

The biggest missing scroll-snap feature I see is the ability to tell a scrolling container to "snap to the next position in this direction", and maybe by extension "which element(s) are currently snapped". In this article clicking an arrow moves the scroll position by a fixed 40px, but it would be very nice to have a proper API that accounts for element sizes, snap alignments, out-of-axis children, etc.

I ended up writing a package a few years ago that does this (scroll-snap-api). It feels so dirty to calculate the styles on every child in the tree just to find scroll snap positions.