How to make an Input system using delegates?

Making a custom Input System using delegates. (I do not want to use the new Unity Input System) Right now I'm stuck on this:

 public static void w(string action){
         if(string.IsNullOrEmpty(action)) delW();
         else {
             Type sInput = Type.GetType("Sinput");
             if(sInput.GetMethod(action) != null)    
                 delW += sInput.GetMethod(action);//.ToMethodGroup();    
         }
     }

I want to know if it's possible to dynamically add methods to delegates like I'm trying to do here (commented is a hypothetical function, since I believe delegates store MethodGroups).

My goal: being able to assign any key a virtually endless amount of actions. Please tell me what I should do, any help is appreciated.

Extra commentary:

• The "w" function gets called whenever W key is pressed. It calls the delW delegate which should store a bunch of methods that are assigned to this key.

• "Sinput" is a class for all my input related things.

• Right now I'm trying to bind keys via a console command "bind [key] {action}"