Good point! Let’s refer to the question in the post title and agree that we would like fulfill the condition:
“the data must sync automatically”
In other words, the moment we change a value in Google Sheets or we add a new column/row, the same happens in Content Manager, without exporting any csv or clicking any button.
You say, we "need to develop the code for (…) reading and writing data from sheets, etc. Is there anything more you could tell us about it? Do you know any examples showing any robust solution and how to do it step by step?