Implementation of SSO on shopify for existing platform users

I have a website and app where people can come and register.

We are now launching eCommerce and want that

  • existing users should be able to use their credential on shopify
  • If user is already logged in on the platform and navigate to shop then they should not required to login again.
  • If user directly come on shop and login then the same should be continue while using the platform.

Now I am looking for the following

  1. Best plugin or third party integration
  2. If anyone has built their own SSO or if there is any code available to implement the same without plugin.