Woocommerce add a Specific Product Attribute as a class to `post_class`

gistfile1.txt

<?php
add_filter( 'post_class', function( $classes ) {
    // Check if WooCommerce is active
    if ( ! class_exists( 'WC_Product' ) ) {
        return $classes;
    }
    global $post;

    $custom_classes = array();

    // Check if the post type is a product
    if ( 'product' === get_post_type( $post ) ) {
        $product = wc_get_product( $post->ID );

        $attributes_to_check = array( 'pa_your-attribute1', 'pa_your-attribute2', 'pa_your-attribute3' ); // Add your attribute slugs here

        foreach ( $product->get_attributes() as $taxonomy => $wc_attribute ) {
            if ( in_array( $taxonomy, $attributes_to_check ) ) {
                $term_slugs = $wc_attribute->get_slugs();
                // Prefix the slug(s) with the taxonomy
                $term_slugs = array_map( function( $slug ) use ( $taxonomy ) {
                    return $taxonomy . '-' . $slug;
                }, $term_slugs );

                $custom_classes = array_merge( $custom_classes, $term_slugs );
            }
        }
    }

    return array_merge( $classes, $custom_classes );
});

Define a list of product attributes here:
$attributes_to_check = array( 'pa_your-attribute1', 'pa_your-attribute2', 'pa_your-attribute3' );
To return the plugin slugs as post_class on single product and in loop.