FacetWP – ignore depth when sorting by display value

<?php

// Add to your (child) theme's functions.php

add_filter( 'facetwp_facet_orderby', function( $orderby, $facet ) {
    if ( 'pa_variety' == $facet['name'] ) {
        $orderby = 'f.facet_display_value ASC';
    }
    return $orderby;
}, 10, 2 );