A couple of thoughts I had about how it should be constructed.
The Final Deck should tell the story of the creation of the app from start to finish.
Start off with talking about the concept presented to you by the client. Go into your initial research and how it informed the decisions you made. Then walk through the process of how you developed the product.
You want to focus on how the research especially the interaction with your users influenced the product’s development.
You also want to focus on the iterative nature of the design process, the number of variations and how each changed based on your experimentation and your interaction with the user.