Extracting data periodically using graphql API interface

We are an analytics company (fuel level and grid electricity) where we provide a full solution - delivery of Sensors, and IOT gateways, install, connect, MQTT, ETL and custom analytics suited to the problem statement.

The current project needs our company server to conduct ETL using graphql API interface. We have used REST APIs in our previous projects but have never used graphQL. We need someone who can set up the first API module for us and we can take it forward post that.