Which method and how to use when loading level data from res folder(json vs cfg)

Godot Version

4.4

Question

I have a sample class like this below

class_name LevelData extends Resource


@export var grid_size:int
@export var level_num:int
@export var starting_shapes:Dictionary[Vector2i, Resource]
@export var shape_requirements:Dictionary[Resource, ShapeRequirement]

starting_shapes values will be string(instead of resource) in the file and i want to read it or convert it to resource (with my own custom method). I tried using cfg files but can not write dictionary. Tried using json file but i dont want to duplicate my class definition by adding code below.

@export var starting_shapes_str:Dictionary[Vector2i, String]

Is there a way to have transient field (meaning not expected from json) for json way? Or should i directly store resource class instead of above?
My all point for above is, i will have level definitions in “res” folder and will read it and render levels accordingly

Easiest way i found is using ResourceSaver and ResourceLoader. Just create instances of your resources and save them in res folder. Not sure whether it will be packaged with application or not.