<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
declare(strict_types=1);

use Magento\Quote\Api\CartRepositoryInterface;
use Magento\Quote\Model\Quote;
use Magento\Quote\Model\QuoteFactory;
use Magento\Quote\Model\ResourceModel\Quote as QuoteResource;
use Magento\TestFramework\Helper\Bootstrap;
use Magento\TestFramework\Workaround\Override\Fixture\Resolver;

Resolver::getInstance()->requireDataFixture('Magento/Multishipping/Fixtures/quote.php');

$objectManager = Bootstrap::getObjectManager();
/** @var CartRepositoryInterface $quoteRepository */
$quoteRepository = $objectManager->get(CartRepositoryInterface::class);
/** @var QuoteFactory $quoteFactory */
$quoteFactory = $objectManager->get(QuoteFactory::class);
/** @var QuoteResource $quoteResource */
$quoteResource = $objectManager->get(QuoteResource::class);
$quote = $quoteFactory->create();
$quoteResource->load($quote, 'multishipping_quote_id', 'reserved_order_id');

$items = $quote->getAllItems();
$addressList = $quote->getAllShippingAddresses();

foreach ($addressList as $key => $address) {
    $item = $items[$key];
    // set correct quantity per shipping address
    $item->setQty(1);
    $address->setTotalQty(1);
    $address->addItem($item);
}

// assign virtual product to the billing address
$billingAddress = $quote->getBillingAddress();
$virtualItem = $items[count($items) - 1];
$billingAddress->setTotalQty(1);
$billingAddress->addItem($virtualItem);

// need to recollect totals
$quote->setTotalsCollectedFlag(false);
$quote->collectTotals();
$quoteRepository->save($quote);