AWS Step Functions now supports AWS PrivateLink
AWS Step Functions now supports AWS PrivateLink allowing you to access AWS Step Functions from VPC-enabled AWS Lambda functions and other AWS services without traversing the public internet. By using AWS PrivateLink, you can access Step Functions while keeping your network traffic within the Amazon network using interface VPC endpoints. Your network architecture is significantly simplified as you no longer need to use an Internet Gateway, Network Address Translation (NAT) devices, or firewall proxies to connect to AWS Step Functions.
Source:: Amazon AWS