Code snippet to enables Meta-compatible checkout URLs for WooCommerce using WebToffee Product Feed - By WebToffee

functions.php

<?php //Do not copy this line of code
add_filter( 'wt_feed_facebook_product_checkout_link', 'wbfte_product_feed_change_checkout_url', 10, 2 );
/**
 * Modify the checkout URL for Facebook product feeds.
 *
 * @param string        $checkout_url The original checkout URL.
 * @param WC_Product    $product      The product object.
 *
 * @return string Modified checkout URL.
 */
function wbfte_product_feed_change_checkout_url( $checkout_url, $product ) {
	if ( empty( $product ) || ! $product instanceof WC_Product ) {
		return $checkout_url;
	}
	$product_id = (int) $product->get_id();
	if ( $product_id <= 0 ) {
		return $checkout_url;
	}
	if ( function_exists( 'wc_get_checkout_url' ) ) {
		$base_checkout_url = wc_get_checkout_url();
		// Build the URL safely with a query argument.
		$modified_checkout_url = add_query_arg(
			array(
				'products' => $product_id,
			),
			$base_checkout_url
		);
		// Store a sanitized URL for further use.
		$checkout_url = esc_url_raw( $modified_checkout_url );
	}
	return $checkout_url;
}

add_action( 'template_redirect', 'wbfte_product_feed_redirect_products_to_add_to_cart' );
/**
 * Redirect products to add to cart on checkout page.
 *
 * Handles URL parameter 'products' and redirects to checkout with add-to-cart parameter.
 *
 * @return void
 */
function wbfte_product_feed_redirect_products_to_add_to_cart() {
	if ( is_admin() ) {
		return;
	}
	if ( ! is_page( 'checkout' ) ) {
		return;
	}
	if ( ! isset( $_GET['products'] ) ) {
		return;
	}
	$product_id = absint( $_GET['products'] );
	if ( ! $product_id ) {
		return;
	}
	// Check if WooCommerce is active and product exists.
	if ( ! function_exists( 'wc_get_product' ) ) {
		return;
	}
	$product = wc_get_product( $product_id );
	// Validate product.
	if ( ! $product || ! $product->is_purchasable() ) {
		return;
	}
	$redirect_url = add_query_arg(
		'add-to-cart',
		$product_id,
		wc_get_checkout_url()
	);
	wp_safe_redirect( $redirect_url );
	exit;
}