Use this snippet to display validation notices before clicking the place order button.

csp-trigger-notices-before-place-order.php

<?php
/**
 * Plugin Name: WooCommerce Conditional Shipping and Payments - Display notices dynamically
 * Plugin URI: https://woocommerce.com/products/conditional-shipping-and-payments/
 * Description: Use this snippet to display validation notices before clicking the place order button.
 * Version: 1.0
 * Author: WooCommerce
 * Author URI: https://woocommerce.com/
 * Developer: Jason Kytros
 *
 *
 * Copyright: © 2021 Automattic
 * License: GNU General Public License v3.0
 * License URI: http://www.gnu.org/licenses/gpl-3.0.html
 */

add_filter( 'woocommerce_csp_validate_shipping_method_on_update_order_review', '__return_true' );
add_filter( 'woocommerce_csp_validate_payment_gateway_on_update_order_review', '__return_true' );
add_filter( 'woocommerce_csp_validate_shipping_destination_on_update_order_review', '__return_true' );

add_action( 'wp_footer', 'sw_force_checkout_update', 0 );

function sw_force_checkout_update() {
	?><script type="text/javascript">
		jQuery( 'body' ).on( 'init_checkout', function() {
			jQuery( 'form.checkout' ).trigger( 'update' );
		} );
	</script><?php
}

This is an ideal solution for our checkout page, but when triggered the right column area that contains the payment methods, purchase items refreshes over and over. Is there anyway to prevent this?