Connecting orders created using Shopify Buy SDK JS with Customers

[pio]

Hello,
I'm looking to create Shopify store using Shopify Buy SDK and Storefront API.

The goal is to:
 - require users to sign up/sign in before they can browse products
   - I understand that this I can achieve using Storefront API and my custom registration/activate/signup pages
   - possibly users need to be approved before being able to log in
- Then I wanted to use Shopify Buy SDK to allow customers to browse and purchase products 
  - How can I ensure that customer authenticated using Storefront API is passed on to Shopify Buy SDK?
  - How do I ensure that the customer is not asked to log in by Shopify Buy SDK?

Is it a correct flow or would there be any other Shopify features that I could leverage?