Add product attribute to CSS classes

add_filter( 'woocommerce_post_class', function( $classes, $product ) {

	// Variations Yield To Parent Product IDs
	if( $product->is_type( 'variation' ) ) {
		$product = wc_get_product( $product->get_parent_id() );
	}

	// Add Product Attribute
	$attribute_slug = 'country-of-origin';
	$coo = $product->get_attribute( 'pa_' . $attribute_slug );
	if( $coo ) {
		$classes[] = 'pa_' . $attribute_slug . '-' . sanitize_title( $coo );
	}

	// Return
	return $classes;

}, 10, 2 );

// Blocks Support
add_filter( 'wp_get_attachment_image_attributes', function( $attr) {

	if( ! class_exists( 'WooCommerce' ) ) {
		return $attr;
	}

	if( is_product() || is_shop() || is_product_category() ) {
		global $product;
		if( $product ) {
			$attribute_slug = 'country-of-origin';
			$coo = $product->get_attribute( 'pa_' . $attribute_slug );
			if( $coo ) {
				$attr['class'] .= ' pa_' . $attribute_slug . '-' . sanitize_title( $coo );
			}
		}
	}

	return $attr;

} );

CSS example:

.wc-block-components-product-image a:has(img.pa_country-of-origin-usa):before,
  body.pa_country-of-origin-usa div.woocommerce-product-gallery:before {
    content: url( '/wp-content/uploads/2025/09/MADE_IN_USA-150x150.png' ) / "Made in USA";
    position: absolute;
    display: inline-block;
    transform: scale( .5 );
    z-index: 1;
    top: -50px;
    left: -50px;
}