Inspector public with movable pivot in editor window.

Well this took me a little while to figure out but this seems to work, just copy it into a file: V3visulization.cs and have it somewhere in your assets folder (doesn't need to be in an 'Editor' folder), the rest should work for Vector3's (I haven't bothered with Vector2's, they shouldn't be hard to add yourself with this start):

 using UnityEditor;
 using System.Reflection;
 using UnityEngine;
 
 [InitializeOnLoad]
 class V3visulization{
     static V3visulization(){
         SceneView.onSceneGUIDelegate += OnSceneGUI;
     }
     
     static void OnSceneGUI(SceneView scnView){
         GameObject selObj;
         Vector3 v3;
         MonoBehaviour[] scripts;
         
         selObj = Selection.activeGameObject;
         if(selObj != null){
             scripts = selObj.GetComponents<MonoBehaviour>();
             for(int i = 0; i < scripts.Length; i++){
                 MonoBehaviour data = scripts[i];
                 FieldInfo[] fields = data.GetType().GetFields(BindingFlags.Public | BindingFlags.Instance);
                 for(int j = 0; j < fields.Length; j++){
                     if(fields[j].GetValue(scripts[i]).GetType() == typeof(Vector3)){
                         v3 = (Vector3)fields[j].GetValue(scripts[i]);
                         v3 = Handles.PositionHandle(v3, Quaternion.identity);
                         fields[j].SetValue(scripts[i], v3);
                     }
                 }
             }
         }
     }
 }

Hope that helps you!

Scribe