Is the WooCommerce store considered a new store and/or a seller in one of the stores?

The WooCommerce Polaris connector links your WooCommerce store to a Polaris store.

During the configuration of the extension, you choose which store your e-commerce site is associated with; it is this store that will be used as a reference for synchronizing the stock and products.

Furthermore, you will also be required to enter the register and vendor identifiers that will be used to create the sales made from the shop.