That’s the current workaround mentioned in the feature request for selling products in bulk . Might be possible to use a coupon as well. https://support.wix.com/en/article/wix-stores-creating-a-buy-x-get-y-free-coupon
As for getting the URL, you can acquire it in the settings for products in the dashboard. https://support.wix.com/en/article/wix-stores-seo-for-product-pages