aws-greengrass-stream-manager-sdk-python upload?

You are correct in your understanding. The AWS Greengrass Stream Manager SDK for Python primarily supports uploading data from the core device to AWS S3, but it does not provide direct functionality for downloading from S3 to the core device.

The Stream Manager is designed to handle data streams from edge devices to the cloud, with a focus on exporting data to various AWS services, including S3. Its main purpose is to manage the flow of data from the edge to the cloud, not the other way around.

For downloading data from S3 to a Greengrass core device, you would typically use a different approach within your custom component. The recommended method would be to use the AWS SDK for Python (Boto3) directly in your Greengrass custom component.

To implement this in a custom component:

1. Include the Boto3 library in your component's dependencies.
2. In your component's code, use Boto3's S3 client to download objects from your S3 bucket.
3. Ensure your component has the necessary permissions to access the S3 bucket.

This approach allows you to have more control over the download process and integrate it seamlessly with your component's logic. It's a more flexible solution for retrieving data from S3 to your Greengrass core device compared to using the Stream Manager, which is optimized for outbound data flow.
Sources
Greengrass v2 upload non-file to S3 using StreamManager | AWS re:Post
Create custom components that use stream manager - AWS IoT Greengrass