About 10 years ago I’ve written this post over here. It also extrudes a sprite / texture but it generates a single quad for the front and back side. The material has to be a cutout shader so alpha == 0 pixels are just removed. The script only generates the side quads, one for each pixel that is a neighbor of an alpha 0 pixel. In theory the script could combine several quads that are in line into a single quad. The post has a gif animation that shows how it actually works:
