This is a new trick for create 2d cloud in Unity or other game engine.
Code write on URP 12.1.7 (Unity 2021) , but shader is not complicate so you can use this shader on lower version of URP without any error, maybe.
1: Model: M_Hemisphere_Inv_Normal.fbx, a hemisphere which has invere normal
2: Textures: 4 textures for 2 types of clouds.
3: Material: 2 materials for 2 types of clouds.
4: Shaders: CloudLayer.shader and CloudLayer.hlsl
5: BlenderFile: a scene which ease to use for render six-way cloud
much appreciate for vfx guru on Twitter, @Samuel Krug and @byccollective sharing thier remarquable experience on cloud rendering !