trail-into-darkness/Packages/com.jovian.utilities/Runtime/EditorRuntimeAccessible/HierarchyUtility.cs

using System.Collections.Generic;
using UnityEngine;
#if UNITY_EDITOR
using System;
using UnityEditor.SceneManagement;
#endif

namespace Jovian.Utilities {
    public static class HierarchyUtility {
#if UNITY_EDITOR
        public static List<TComponent> FindComponentsInHierarchy<TComponent>(bool includeInactive = false) where TComponent : Component {
            PrefabStage prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
            if(prefabStage == null) {
                return SceneUtility.FindComponentsInActiveScene<TComponent>(includeInactive);
            }
            else {
                return new List<TComponent>(prefabStage.prefabContentsRoot.GetComponentsInChildren<TComponent>(includeInactive));
            }
        }

        public static List<Component> FindComponentsInHierarchy(Type componentType, bool includeInactive = false) {
            PrefabStage prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
            if(prefabStage == null) {
                return SceneUtility.FindComponentsInActiveScene(componentType, includeInactive);
            }
            else {
                return new List<Component>(prefabStage.prefabContentsRoot.GetComponentsInChildren(componentType, includeInactive));
            }
        }
#endif
    }
}