Today i decided to open a godot feature proposal for adding a way to make custom VisualShader nodes using the VisualShader editor itself, instead of writing them as a script!
Go take a look and... interact? with it? in some way? if you're interested.
I don't really know how godot proposals get turned into features, but i figure this is a pretty well-defined use case and i haven't seen any other proposals or issues about it so i'll do one myself.