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 );

CSS example:

ul.wp-block-woocommerce-product-template li.pa_country-of-origin-usa {
	position: relative;
}

ul.products li.pa_country-of-origin-usa:before,
body.pa_country-of-origin-usa div.woocommerce-product-gallery:before,
ul.wp-block-woocommerce-product-template li.pa_country-of-origin-usa:before {
    content: url( '/wp-content/uploads/2022/06/MADE_IN_USA_bug_round_r3-150x150.png' );
    position: absolute;
    display: inline-block;
    transform: scale( .5 );
    z-index: 1;
    top: -50px;
    left: -50px;
}