GLES2 is now supported in the main development branch. This should help with support for embedded devices (phones, raspberry pi, etc).
When building, specify -DMAGNUM_TARGET_GLES=ON -DMAGNUM_TARGET_GLES2=ON at cmake time, for example:
$ cmake -DMAGNUM_TARGET_GLES=ON -DMAGNUM_TARGET_GLES2=ON -DCMAKE_BUILD_TYPE=Release -DENABLE_CLIENT=TRUE -DENABLE_SERVER=FALSE -DENABLE_PLUGINS=FALSE ..
$ make -j$(nproc)