Help with Offhand/Sneak Right Click

I'm confused how to make an consumable advancement only work if the item is in offhand or the player is sneaking. This is my attempt to do offhand.
{
  "criteria": {
    "use": {
      "trigger": "minecraft:using_item",
      "conditions": {
        "item": {
          "predicates": {
            "minecraft:custom_data": {
              "relic": "box",
              "slot": "offhand"
            }
          }
        }
      }
    }
  },
  "rewards": {
    "function": "relic:crazyitemsadvancement"
  }
}