After looking for a sparkle/glitter shader implementation and only finding THIS pdf from AMD (Page 22). I found the AMD implementation lacking as it is grid based which is clearly visible in my opinion, so I decided to roll my own.
Three example shaders is included
Example shader 1: Only sparkles.
Example shader 2: Sparkles combined with a barebones diffuse+specular setup
Example shader 3: Sparkles combined with reflection and refraction for a bit of fancyness
The shaders are visible in action at https://westmark.itch.io/sparkleshader