Custom lighting blend between 4 lightmap textures to create a static day-night cycle with no real-time lighting. Dynamic objects use reflection probe LOD to create the impression of indirect lighting. Simple extraction of Main Light color and Direction to create "direct" lighting on dynamic objects without needing full runtime lighting.
Everything created in Shader Graph using Unlit shader.
Some techniques derived from Unity custom lighting blog post: https://blogs.unity3d.com/2019/07/31/...