I created my first Shopify app recently for the app challenge, I used Python and found it took me quite a while to fully understand the entire app flow (there's a lot to digest). I decided to create a very small, simple but complete app for Shopify. I've posted it to GitHub and it is free to use for anyone:
Hopefully this helps anyone starting out wanting to use Python get going a bit faster.
If you have questions or issues, just let me know here and I'll be happy to help where I can.
Thanks for sharing your tutorial! It is very helpful. I am having an issue where right after I select my development store to test the app, it takes me to a page that says:
"Oauth error invalid_request: The redirect_uri is not whitelisted"
I have double checked that the ngrok link in the Shopify app setup is the same as the one in config.py. Any help would be greatly appreciated. Thanks!!