How to convert interface to a GameObject

I am making a weapon system for my game, and I need to instantiate my weapon for the player to use. The problem is that I have an interface called IPickupable, and then a list of Type IPickupable.

 public List<IPickup> allEquipable;

As of now I only have one GameObject in there, which has the interface IEquipable, and IPickup.

The Pistol you see is basically just a Prefab object that has a script called weapon, that inherits multiple interfaces. Mainly IEquipable and IPickupable.

And then for the player, I have another list with every one of his picked up items.

 public List<IPickup> inventory = new List<IPickup>();
 public IEquipable currentItem;

And as you can see I also have an interface with IEquipable, that's everything the player can equip and use. The IEquipable go on things like weapons and stuff.

So now I have a system, when the player spawns it automatically gives the player Pistol. Which I find by doing this:

 var IitemToEquip = GameController.GC.allEquipable.FirstOrDefault(x => x.PickUpName == "Pistol");

So now I want to convert that interface to the Prefab that inherits that interface. Afterwards I want to check if that interface is an IEquipable, and if so.. Instantiate it. But I have no clue how to do that. Thanks for the help.