Can you draw charts from external data sources?

You should totally be able to do this. 

1. Check to make sure your model is retrieving data (in the console with “skuid.$M(‘YourModelName’).data”,  or with a table.
2. Start checking properties of your chart. 

Anna recently posted a sample page that calls a Rest API and renders it as a Chart.  We showed this one off at Dreamforce. 
https://github.com/skuidify/SamplePages/blob/master/pages/Country%20Analysis%20(REST%20example)