I see the AWS publish API for sending push notifications to devices. http://docs.aws.amazon.com/sns/latest/api/API_Publish.html
According to: https://aws.amazon.com/blogs/aws/push-notifications-to-mobile-devices-using-amazon-sns/ We can "Send messages directly to a specific device by calling the Publish function using devices ARN. You can easily scale it to handle millions of users by storing ARN endpoints in Amazon DynamoDB and using multi-threaded code on the server. "
If I want to send push notifs to 100K users (who have not registered in a particular topic), is there an API with multiple publications (or batch-publish) where I do not need to call the “Push” API notifications for each individual user?
probably not. devices must be registered (i.e. for SNS you really need to create an endpoint for each device). Once you have an endpoint, you can subscribe to one or more SNS endpoints and start publishing notifications through them.