One thing needs to change first:
Redo the slider, but do not delete the slider nav buttons (bullets) at the bottom of the slider. Give it a class and hide them instead.
Then paste this in Page Settings > Custom Code > Footer Code:
<script>
var Webflow = Webflow || [];
Webflow.push(function() {
$('.choicescolumn').on('change', '#os3, #os3-1, #os-8', function() {
$(this).parents('.productrow').find('.w-slider-dot').eq(this.selectedIndex).trigger('tap');
});
});
</script>