What does the Service Access - S3 Enabled really means under the hood?
Service Access - S3 Enabled in VMC on AWS enables the necessary configurations for SDDC components to access S3 using Interface Endpoints.
What is the SDDC ENI and is this the only interface between the SDDC and Connected VPC or there are more interfaces as recall seeing diagrams showing each ESXi Host having an interface in the Connected VPC?
The SDDC ENI facilitates communication between the SDDC infrastructure and AWS services, including S3.
Connectivity between VPCs or between the SDDC and other AWS resources might involve various networking components and configurations beyond the SDDC ENI. It could include VPC Peering, Direct Connect, or other networking constructs based on your specific setup and requirements.