FacetWP – index disabled variations (post_status = private)

<?php

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

add_filter( 'facetwp_indexer_query_args', function( $args ) {
    if ( in_array( 'product', (array) $args['post_type'] ) ) {
        $args['post_status'] = [ 'publish', 'private' ];
    }
    return $args;
}, 20 );