I was able to create 2D Normal Map reflections using GDevelop Light object 
The current system supports:
- Multi lights reflections in the same time.
- Green channel flip (Flip Y).
- Takes gdevelop ambient light color into account.
- Takes the light object radius into account.
- Respects light obstacle behavior.
- Sprite animations.
- Light object color.
- Ambient boost.
- Intensity.
- Pixel perfect & smooth.
And much more ! :3
Most likely I will turn it into an extension to make it super easy for everyone to use 
