Advanced DynamoDB Streams Event Driven Architecture

Act as a Serverless Data Engineer. Architect a highly decoupled, real-time event-driven synchronization pipeline where high-velocity `INSERT` and `MODIFY` changes originating from the [DYNAMODB_TABLE] reliably trigger complex updates across multiple [DOWNSTREAM_TARGETS]. You must surgically address potential API throttling and Lambda concurrent execution limits. Detail the precise integration path from DynamoDB Streams into AWS EventBridge Pipes or SNS for a massive fan-out pattern. Provide the exact Lambda handler Python code enforcing idempotency, parsing the complex [EVENT_PAYLOAD] (stripping the DynamoDB `{S: }` type wrappers), and implementing strict Dead Letter Queue (DLQ) routing to absolutely guarantee zero data loss during massive traffic spikes.