Here is a very simple app which will extract posts and comments to excel.
Hey you can just automate this task for free using Wyzebulb.
They let you start it for free with 300 actions and post that the cost is very minimal compared to other similar products.
I'm using Wyzebulb and it allows you to do this in real time.
Wyzebulb pushes the data into Google sheet in less than a minute of the comment being written.
Here is a video tutorial link on how to do this automation:
Also, you can filter data being pushed into the Google Sheet. For Example, you only want to push usernames to the Sheet, Wyzebulb provides you with filters to perform this task. This feature saves a lot of time as going through comments manually is a time consuming and meticulous task.