They are a popular, budget-friendly alternative to complex 3D VTuber models, allowing artists to showcase their OC (Original Character) designs.
The name doesn't appear to be a famous or viral image on its own, but it most likely refers to a PNGTuber model —a common tool used by content creators who want to stream without showing their real face. What is a "Little PNG" Character? LittleLi4.PNG
There is a Little PNG Shop that sells island-style apparel and products. They are a popular, budget-friendly alternative to complex