The lasers, in both the standard and pixel art styles, are just shaders applied to Line2Ds; no images or GIFs (except for some particles). The pixel art version is a modified version of the original shaders in which I changed some code and parameters, used a pixelation technique, and set up the particle systems with a pixel art style.
The structure of my lasers is as follows:
Where Laser contains the ShaderMaterial with its shader.
Hope this helped you. Feel free to ask anything.