solution to read csv from bucket with API Gateway for ADX API Product

Hello, I store data in S3 as part of Amazon Data Exchange Products. I want to create an API product so that users can pull my data in csv or json format directly from the bucket. The bucket contains multiple csv's per day Do I need a lambda fronting an api in api gateway which will read the contents of the file first? Or, can I simply create an API which will parse the files and return data to the subscribers? I would then package that API up into a "data product" Ideally the data would be pulled as json by default, but they would also be able to pull it as csv. I will need to be able to give users the ability to structure a payload via SDK or CLI or some other IDE in which they specify various fields, date ranges etc... Thank you.