To add any Substack data sources to your app, just add the main base url as the source and set the data_type to substack.
from embedchain import Appapp = App()# source: for any substack just add the root URLapp.add('https://www.lennysnewsletter.com', data_type='substack')app.query("Who is Brian Chesky?")# Answer: Brian Chesky is the co-founder and CEO of Airbnb.