Currently Sellbrite does not directly integrate with any in-store point of sale system. However, there are 2 POS systems that can be connected indirectly to Sellbrite by way of a shopping cart: Shopify POS (for Shopify) and Amber POS (for BigCommerce).
Why Shopify and Amber?
If you're using Shopify POS in conjunction with a Shopify store, all orders are generated in the same place and will be retrieved by Sellbrite. Similarly, if Amber POS is connected to BigCommerce, Amber will actually generate an order within BigCommerce for Sellbrite to retrieve, and when Sellbrite updates inventory in BigCommerce, Amber is updated as well.