Here is why you can see all your product status as "opted in" when you sign up for the Google Shopping Feed app.
As soon as you complete the setup process for the Google Shopping feed, you will notice that the product status shows as "opted in" by default. This implies that we have attempted to push your products to Google Merchant Center after successfully selecting a subscription plan.
However, the "opted in" status is temporary. After Google has successfully analyzed the products, you will see the status has changed to "approved," "disapproved," or "approved with warnings."