Rainy Glass/Wet Lens Shader
I've constructed a Wet Lens Shader/Rainy Glass Shader in Amplify Shader. The rain effect is created by a scrolling tileable texture. There are speed parameters that are configurable for the panning on the X and Y axis. The material has inputs for 3 textures (Rain Specks Normal Map, Rain Streaks Normal Map, and Rain Streaks Mask). I've posted a preview of my shader node network for those of you who are interested.