It's completely up to you which drivers you use, as it is for all image builders.
But if you made yourself dependant on an external party (the factory), you should ask them to supply the GLES-drivers, as well as the required changes to use them.
We have BSP layers an the manufacturer should update these....As soon these are adapted we also have the 'GLES-drivers'. And indeed we are depended here.
Note that it is not our goal to support as much boxes as possible an put if box x than do y structures in enigma2......