Woocommerce: Different shipping methods for different products in single cart

two-shipping-in-cart.php

/** Seperate freepromo products from other Items - forcing multiple carts **/
add_filter( 'woocommerce_cart_shipping_packages', 'ps_two_shipping_methods_in_cart' );

function ps_two_shipping_methods_in_cart( $packages ) {
   $packages = array();
   $freepromo_items = array();
   $regular_items = array();
   $freeshipclass= 'freepromo';
   $shipto = array(
                'country' => WC()->customer->get_shipping_country(),
                'state' => WC()->customer->get_shipping_state(),
                'postcode' => WC()->customer->get_shipping_postcode(),
                'city' => WC()->customer->get_shipping_city(),
                'address' => WC()->customer->get_shipping_address(),
                'address_2' => WC()->customer->get_shipping_address_2()
    );

    // Sort freepromo from regular
    foreach ( WC()->cart->get_cart() as $item ) {
        if ( $item['data']->needs_shipping() ) {
            if ( $item['data']->get_shipping_class() == $freeshipclass ) {
                $freepromo_items[] = $item;
            } else {
                $regular_items[] = $item;
            }
        }
    }

//If product qualifies for free shipping
    if ( $freepromo_items && WC()->customer->get_shipping_country() =='US' ) {
        $packages[] = array(
            'ship_via' => array( 'free_shipping'  ),
            'contents' => $freepromo_items,
            'contents_cost' => array_sum( wp_list_pluck( $freepromo_items, 'line_total' ) ),
            'applied_coupons' => WC()->cart->applied_coupons,
            'destination' => $shipto
        );
    }elseif ( $freepromo_items ) { //if product does qualify for free shipping but customer is not in US
        $packages[] = array(
            'ship_via' => array( 'usps','ups'  ), //available shipping methods for international
            'contents' => $freepromo_items,
            'contents_cost' => array_sum( wp_list_pluck( $freepromo_items, 'line_total' ) ),
            'applied_coupons' => WC()->cart->applied_coupons,
            'destination' => $shipto
        );
    }


//If product does not qualify for free shipping
    if ( $regular_items ) {
        $packages[] = array(
        	'ship_via' => array( 'usps','ups'  ),
            'contents' => $regular_items,
            'contents_cost' => array_sum( wp_list_pluck( $regular_items, 'line_total' ) ),
            'applied_coupons' => WC()->cart->applied_coupons,
            'destination' => $shipto
        );
    }   
   
    return $packages;
}

Awesome, very helpful!