http://Singer.io is an open source ETL project written in Python. The components are small, composable programs that you can run independently, so you should be able to walk before your run.

A good beginner project is to build an adapter to a new data source (known as a "tap" in Singer). Most taps pull data out of business tools like Salesforce or Marketo, but people also build them to pull characters from the Marvel API (https://www.stitchdata.com/blog/tapping-marvel-api/)

Check out the getting started guide (https://github.com/singer-io/getting-started), or jump into the Singer Slack and ask for help (linked from the guide)