Great question! See https://www.infracost.io/docs/features/usage_based_resources... as the CLI can pull usage data for Lambda/S3/Dynamo from the AWS APIs (e.g. CloudWatch).

The other data source we can tap into is the actual billing data, e.g. AWS Cloud and Usage Reports - if you have any thoughts/preferences, checkout https://github.com/infracost/infracost/discussions/985#discu...