How to add a postal code field to the POS cart in Shopify?

Hello,

I am setting up Shopify eCommerce and POS.

I am launching my first physical store and want to collect the postal/zip codes of each customer in the store so I can understand where my customers based.

On the cart before the shop attendant I want add a required field Postcode.

How do I add this to the Shopify POS Cart?

Thank you

I’m also interested in adding this to my POS Cart, but it doesn’t seem to be an option. Can anyone help with this issue?