How to add customer checkout screen in WooCommerce POS Mobile App?

Well, first for the web based WooComerce POS system if you want have this particular functionality then you have to install the WooCommerce POS Customer Checkout plugin.

WooCommerce POS Customer Checkout plugin that allows the customers to use the POS and place the order themselves without the hassle of going to POS agents.

Now, you can also integrate the similar functionality within the WooCommerce Native Flutter POS App via customization(A Paid Service).