CODE EXAMPLE FOR CSHARP

unity find all scriptable objects of a type

 public static T[] GetAllInstances<T>() where T : ScriptableObject
     {
         string[] guids = AssetDatabase.FindAssets("t:"+ typeof(T).Name);  //FindAssets uses tags check documentation for more info
         T[] a = new T[guids.Length];
         for(int i =0;i<guids.Length;i++)         //probably could get optimized 
         {
             string path = AssetDatabase.GUIDToAssetPath(guids[i]);
             a[i] = AssetDatabase.LoadAssetAtPath<T>(path);
         }
 
         return a;
 
     }