Iron Sights;1958566
I'm guessing this applies to the other mod chips aswell?
Almost certainly.
Not sure about the DS, but older Nintendo hardware, the GBA, checks the rom image for a specific bitmap (a picture of mario IIRC), if the picture is there it boots.
The picture is copyright ;)
This makes the arguement about homebrew moot, because to get any homebrew to boot from a cart without modifying the hardware directly, you have to violate Nintendo's copyright by copying the image.