I have looked very closely and while the main cables like the shifter cables are internal once they enter behind the stem and I would assume most of the rear brake, the front brake will have to be exposed because the cable needs to enter the brake noodle well outside of the frame. Also when I mentioned switching out the aerobars or even using the existing aerobars means that you have to have the cables exit the aerobar extensions and go into the frame.

Full internal routing to me means a bike like the Trek Speed Concept where all of the cable are hidden.

This is full internal routing. Not brake noodles sticking out, not brake cables sticking out, not shifter cables sticking out.

Chinese frame not. Depending on the price of the frame and of course how creative you are it might not be that bad for the money. Will just not be that clean of a run using those style of brakes. Look at other bikes that use that design and you will see what I mean.