WooCommerce - Restrict Shipping Zone by Shipping Class

functions.php

<?php
// Adding notice to product availability text
function wdt_extend_availability( $availability, $product ) {

    $target_shipping_class = 'dropshipping';

    if ( $target_shipping_class == $product->get_shipping_class() ) {
		
        $availability .= '<p class="shipping-class-notice">Diesen Artikel versenden wir <b>nur innerhalb Deutschlands</b>.</p>';

    }

    return $availability;
}

add_filter('woocommerce_get_availability_text', 'wdt_extend_availability', 10, 2);

// Restricitng Shipping Class & Shipping Zone combination in Cart
function wdt_restrict_shipping( $available_methods, $package ) {

	// Set the shipping class and shipping zone you want to restrict
    $restricted_shipping_class = 'dropshipping';
    $restrict_to_zone = 1;
	
	// Shipping zone
    $shipping_zone = wc_get_shipping_zone( $package );
    
    // Get zone ID
    $zone_id = $shipping_zone->get_id();
	if ( $zone_id != $restrict_to_zone ) {
		
		foreach( $package['contents'] as $cart_item ) {
			
			if ( $cart_item['data']->get_shipping_class() == $restricted_shipping_class ) {
				
				wc_clear_notices();
				wc_add_notice( __('Den Artikel <b>'.$cart_item['data']->get_title().'</b> versenden wir <b>nur innerhalb Deutschlands</b>.'), 'error' );
				unset( $available_methods );
				break;
				
			}
		
		}
	
	}

    return $available_methods;
}
add_filter('woocommerce_package_rates', 'wdt_restrict_shipping', 10, 2);