Thank you Sergio! If you see the Part 2 of this article, I explain how to_sql is an extremely slow method for large amounts of data. It was simply unpracticable for us to use it. If it fits your use case, by all means skip the staging table part!
Thanks for your response. I have clearly explained what Data Lakes and Data Warehouses are, why and how we use them, and finally explained my solution for migrating data from one to the other. If you can be clearer about what you didn’t understand, I can help you better.