Hey! I stumbled across this game just now. I like the idea, you could probably gamify it more. If you add a score counter or some obstacles you have to avoid while moving a ball, it could become a fully fledged game!
If you want to keep a sandbox feel, you could make this a cool sandbox, where you get points for doing cool tricks with the ball, like throwing it in the air, or doing a flip if you ramp up the rotation speed to gain some points. You could also use the Godot's lerp function to have the block rotate faster the longer you press maybe?