This is a method to add your own items to Shopify's member registration form without using an app and register them as tags or notes. By using Shopify Flow in conjunction with this, you can also reflect the input values in meta fields. Here is an example of how to set it up.
How to set a birthday input field on the account creation screen and set the entered value as a customer tag and metafield
[Setting Method 1] Add the code to the main-register.liquid form
[Setup Method 2] Create a Flow that uses customer creation as a trigger to identify customer tags and set metafield values.
