We run Meltano in Kubernetes with AWS EKS and our jobs run with a Kubernetes ServiceAccount mapped to an AWS IAM role with S3 access. Currently, we use tap-spreadsheets-anywhere to extract CSV data from AWS S3 using short-lived tokens via sts:AssumeRole (AWS_WEB_IDENTITY_TOKEN_FILE and AWS_ROLE_SESSION_NAME environment variables).
In tap-spreadsheets-anywhere the tap just uses boto3 and this behavior is provided out-of-the-box. I'm interested to try this tap-universal-file extractor but it seems to only allow long-lived access key and secret credentials for S3.