"My Addresses" is different from Contact's info

Question:
How would I access information programmatically under the My Address page?

Product:
Wix Editor, Wix Stores, Wix Members, Velo

What are you trying to achieve:
I am trying to create a form for customers to provide more information about their delivery address as my company has some products that are particularly heavy/bulky and we want to include special delivery solutions for these products.

As such, I have set up a repeater and am trying to dynamically map the addresses saved in My Addresses so that customers can fill up a form for each address to indicate instructions for special deliveries. I have also set up some custom text fields in the Checkout page for customers to include these instructions.

I would like to consolidate the fields in the form with the information in Checkout page, i.e. if customers have filled out the fields in Checkout, I would like them to be reflected in the form in my repeater and be editable there.

But most importantly I would like to find out how I can access the addresses saved under My Addresses programmatically so I can automate the calculations for special deliveries using information declared within. I assume the custom text fields are stored via a reference within My Addresses as well.

What have you already tried:
I found an old article by @mrgnhnt96 but looks like they were looking for ContactInfo and not how to manipulate info in the My Address page.

The Wix/Velo documentation gives instructions as to how to add these custom fields to Checkout and allows you to name the fields so that “they can be accessed in code” but provides no information as to how to do so (no CMS id, no methods to do so…).