This combines Miguel Grinberg's Flask Mega Tutorial with his OAuth Authentication with Flask tutorial. I only go through chapter 5 of his Mega Tutorial because that's where you would need to add his OAuth stuff instead of OpenID. There are comments in the code to hopefully explain all of the changes you need to make. There aren't too terribly many.
There are known bugs that will occur as you move further into the Mega Tutorial, and I will list them in the github issues. I suggest you try to resolve those bugs yourself, but if/as I have time, I will resolve those issues in my own code.
If you have any questions, create an issue in this repo. I found it difficult to find the help I need and I'd like to make this a helpful resource for people.