Many store owners that own several WooCommerce stores wish to have a common cart/checkout for all their stores so that customers can pick and add products from several stores and pay in one single checkout. But that is not possible, and here is why.
Due to the way WP multisite and WooCommerce works its not possible to have a global/ common/ single/ universal cart or basket and checkout for several WordPress WooCommerce shops. This feature has been asked by users to Woo developers for years now, but never been implemented. The main reason is the database structure and the code workflow The real problem are the cookies and data which are available through a domain, but not other domains even if they are «within» same WordPress network. Even if there could be an extend for this to make a «fix», there’s no way to share the cart across other domains.
So for now we have to conclude that WordPress can use WooCommerce in a network like this, but miss the possibility to add the feature of a global cart and checkout.