Something like this. Probably some kind of noise mask with some metallic, low roughness?
By changing the strength of the normal map, you can change how non-flat the glitter effect is, and the size with the Voronoi scale.
If the object will be moving or animated, it would be recommended to plug a UV Map Node into the Voronoi Texture
This method also works great for snow, car paint, and anything else that has a glitter to it!