Great Idea and direction, not so great execution.
There absolutely must be more notes telling you what is in godot already and what was pre programmed for this specific tutorial.
Just little "*" things with text like "*hey, this "amount" thing is a variable we hid behind the scenes, you don't see it, but it's there and we'll change it to test different things"
A lot of things are in what feels like the wrong order, stuff like variables should probably be taught before you get into contact with them at all, not after. You just end up seeing a lof of things on screen you have no idea about.
Other than that, It's a great learning tool. It just needs some thoughtful reworking.