Well, the thing is this:
Pyglet is in fact a wrapper just like xlib_wrapper. It needs to fetch stuff from the header in order to know how to work with OpenGL ES.
Thats how the default OpenGL module on computers work, too.
How else can it be working with the APIs on the host computer? :P

It seems like the headers arent present on my phone or in the repositories (I have devel activated.)...
How do you get them?