Documentation completely out of date; as a result, unable to connect to Shopify

Examples:

• At https://www.drupal.org/node/2479703, it still gives instructions to install the Shopify API module, which was supposedly removed as a dependency a couple of years ago.
• The "Help" instructions at /admin/config/system/shopify_api do not match the current Shopify interface at all.
  • It seems you need to go to app development and create an app. There is no "Private Apps" section.
  • For the API settings, there is no "password" or "shared secret". Instead there are an "API secret key" and a "Storefront API access token".
  • These keys and tokens do not work no matter which of the fields they are entered into: "API Error: [API] Invalid API key or access token (unrecognized login or wrong password)". So it seems impossible to connect to the Shopify store. It seems that the module does not work at all, but maybe with better documentation I could be proved wrong.
  • Does this connect via the Storefront API? Or is it the Admin API?
  • The documentation says nothing about the scopes (permissions) needed.

Actually, it would be super useful if a corresponding "Drupal Sales Channel" Shopify app were developed that was set up to connect with this Drupal module, sparing users most of these headaches.