Topics could be:
How to optimize, when to use an animation player vs animated sprite, what is the benefits/ limitations.
How to write the most efficient code, type hints etc
Advanced Exporting for Mobile could be included, I know Master Mobile Game Development with Godot 4: From Concept to App Stores | GameDev.tv is a great class but is sadly out of date. so an update to it could be included.
Maybe something like Godot 4 Shaders: Craft Stunning Visuals | GameDev.tv only for optimization.
I would buy it.
Patrick