The point of the VPC endpoint is that you’ve whitelisted the external services and have a special transparent access to S3. With a CloudFront proxy you’d have

The point of the VPC endpoint is that you’ve whitelisted the external services and have a special transparent access to S3. With a CloudFront proxy you’d have to open up access to all of CloudFront’s potential IP addresses to allow the initial request to complete (which would then redirect to S3). Plus the traffic would need to leave your VPC.