BGL is deprecated and will not work on Metal devices. Although the inital plan was to remove it in Blender 4.0, We don't see any harm to still have it in the code-base until OpenGL itself is deprecated. Add-on developers are warned when using the BGL module that the add-on/script will not work on all platforms. There are still some limitations inside the GPU module that needs a more friendly API. This API isn't clear at this time.
Blender is the free and open source 3D creation suite. It supports the entirety of the 3D pipeline-modeling, rigging, animation, simulation, rendering, compositing, motion tracking and video editing.
Blender as a whole is licensed under the GNU General Public License, Version 3. Individual files may have a different, but compatible license.
See blender.org/about/license for details.