In Blender we can edit the active scene using a node based interface that looks like the image above. We can for example create shaders that way and so on. When these graphs become too complex, or when you need to re-use the same thing multiple times you can create groups and define an input and output for the group.
Is something like that possible in Godot 3/4? Note: I found how to create my custom Godot visual shader nodes. It's definitely interesting but still inside Godot shaders I cannot import, and thus re-use other shader files so that solution wont suffice.