We are currently looking into enabling some SSO feature that will allow Shopify users to log in on our app through their Shopify credentials. This feature can then be used in your marketplace.
However for this we have one blocking point. We need to know the email address and a unique ID for the Shopify user associated with the authentication token we have. We had a look at your API and have seen that the "Retrieve the the currently logged-in user" method is perfect for this (https://help.shopify.com/en/api/reference/plus/user#current-2020-01). However it's only available for Shopify Plus stores.
Would you be able to propose another API method that has the same functionality, but is available to all Shopify stores? Or is there any possibility that single method could be made available for all Shopify stores?
I can see many use cases for this, so I'm a bit surprised it's not made available to all stores. Getting the admin of the store is not sufficient, we really need to know the user the authentication token belongs to.