Create a clone of the Lambda function in AWS Account B so that it can access the DynamoDB table in the same account

Create an IAM role in Account B with access to DynamoDB. Modify the trust policy of the execution role in Account A to allow the execution role of Lambda to assume the IAM role in Account B. Update the Lambda function code to add the AssumeRole API call

Add a resource policy to the DynamoDB table in AWS Account B to give access to the Lambda function in Account A

Create an IAM role in Account B with access to DynamoDB. Modify the trust policy of the role in Account B to allow the execution role of Lambda to assume this role. Update the Lambda function code to add the AssumeRole API call