You can now route streaming (for example – pixel, USB, user input, audio, clipboard, file upload/download, and printer) traffic to your Amazon AppStream 2.0 streaming instances through your Amazon Virtual Private Cloud (Amazon VPC) using VPC endpoints. You can also use a VPC endpoint to perform API operations without relying on an internet connection. With this feature, the network connection between your users and your AppStream 2.0 streaming instances and your API operations can be restricted to private network routes, further securing your applications. VPC endpoints for AppStream 2.0 are provided by AWS PrivateLink, a highly available, scalable technology that enables customers to privately connect their Amazon VPC to supported AWS services.
from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/08/amazon-appstream-2-now-supports-amazon-virtual-private-cloud-endpoints-for-api-operations-streaming-traffic/