The Shopify POS integration allows you to edit customer fields directly within the Shopify POS app for iOS and Android.
Enable Shopify POS Integration for Paid Plans
By default the app will not work through Shopify POS, you must go to the settings page and click the "Enable" button. You may be required to authorize additional app permissions for reading order history, this is required for the app to work in Shopify POS.
Once you have Shopify POS enabled you can hide specific fields from Shopify POS. Simply go to edit a field and check the "Hide field in Shopify POS" checkbox. Note that the password field is always disabled in Shopify POS.
Using the app in Shopify POS
Select the three dots menu in the top-right when in the cart view when you have a customer selected. You can select an existing customer or create a new one.
Select "Edit Customer Fields" app.
Edit your customer fields and click the "SAVE" button.
You should see a success message letting you know the fields were saved properly.