I’m working on creating a simple blogging Application for a family member who doesn’t have any experience with programming
Since I don’t particularly feel like building an entire authentication service and user interface for creating new blog posts I was wondering if it would be to use google docs as a type of “backend” for the blog. Where the blogs owner can create a new document for a blog entry and then the text from that document appears as a new blog entry on the wesbite
I suggest using Google Sheets. There are lot of guides on how you can use the Google Sheet as backend. Refer to this Stackoverflow post which has multiple answers and suggestions: Can we use Google Spreadsheet as a backend database
Also here's a more detailed guide on how you can set it up: How to Use Google Spreadsheet as a Backend for Your App
As for your idea to use the Google Drive and multiple Google Docs file for every blog, this is also possible however it is going to be much more complicated. Try starting with setting up the Drive API and test if you can pull some data.