Index the country from an ACF “Google Maps” field

<?php

add_filter( 'facetwp_index_row', function( $params, $class ) {
    if ( 'country' == $params['facet_name'] ) {
        $details = $params['place_details'];
        $params['facet_value'] = $details['country'];
        $params['facet_display_value'] = $details['country'];
    }
    return $params;
}, 10, 2 );