Optional/Maybe type for Blueprint?

At work we are currently investigating how we could add a reasonably sane optional type for blueprint.

We have modified the native TOptional type heavily, to make it more convenient, by adding Map()/Bind()/Flatten() methods.

Now we would like to add a similarly convenient optional type for Blueprint use.

We have already started working on a UBlueprintCompilerExtension to detect invalid pin connections, but we haven't started on the actual data type itself.

Does anyone know about a plugin that offers this functionality?

Or, alternatively some good resources on how one can write custom Blueprint graph nodes with wildcard pins?