To add the custom spyglass items into the loot chest of your choice please get the vanilla loot table .json file from a minecraft version.jar
Paste the code at the bottom of the file between these lines inside a loot table .json file:

LAST PART OF EACH JSON DOCUMENT:

    }
  ],
  "random_sequence": "minecraft:chests/abandoned_mineshaft"
}

Paste the SPYGLASS CODE here:

    } <-- YOU PUT YOUR MOUSE BEHIND THIS "}" SYBOL AND PASTE THE CODE
  ],
  "random_sequence": "minecraft:chests/abandoned_mineshaft"
}


SPYGLASS CODE:
you select everything including the , here on the first line:


,
    {
      "bonus_rolls": 0.0,
      "rolls": 1.0,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "minecraft:spyglass",
          "weight": 1,
          "functions": [
            {
              "function": "minecraft:set_components",
              "components": {
                "minecraft:custom_model_data": {
                  "strings": [
                    "1999"
                  ]
                },
                "minecraft:custom_data": {
                  "spyglassme_type": "shrinking_glass"
                },
                "minecraft:custom_name": {
                  "text": "Shrinking Glass",
                  "color": "#00BFFF",
                  "bold": true
                },
                "minecraft:lore": [
                  {
                    "text": "Look at entities to shrink them.",
                    "color": "gray"
                  },
                  {
                    "text": "Be careful not to lose them!",
                    "color": "#FF6347"
                  }
                ]
              }
            }
          ]
        },
        {
          "type": "minecraft:empty",
          "weight": 1
        }
      ]
    },
    {
      "bonus_rolls": 0.0,
      "rolls": 1.0,
      "entries": [
        {
          "type": "minecraft:item",
          "name": "minecraft:spyglass",
          "weight": 1,
          "functions": [
            {
              "function": "minecraft:set_components",
              "components": {
                "minecraft:custom_model_data": {
                  "strings": [
                    "1999"
                  ]
                },
                "minecraft:custom_data": {
                  "spyglassme_type": "growing_glass"
                },
                "minecraft:custom_name": {
                  "text": "Growing Glass",
                  "color": "#FFD700",
                  "bold": true
                },
                "minecraft:lore": [
                  {
                    "text": "Look at entities to grow them.",
                    "color": "gray"
                  },
                  {
                    "text": "May you grow strong and tall!",
                    "color": "green"
                  }
                ]
              }
            }
          ]
        },
        {
          "type": "minecraft:empty",
          "weight": 1
        }
      ]
    }