Something like this might work: Instead of a single file, write multiple files under an S3 prefix. All keys under that prefix are your "file." Write a lambda to

Something like this might work: Instead of a single file, write multiple files under an S3 prefix. All keys under that prefix are your "file." Write a lambda to read all the keys under that prefix and set it up through API gateway to return a single "file." You could also write another lambda to periodically merge multiple s3 keys. It might be slow. Dynamo is probably better.