You can make a product hidden from your main storefront so only selected customers can access it. This will mean the product is ‘exclusive’ to those you share the product with.
How to create a hidden product:
Create the product listing and ‘duplicate’ it in the “Manage Products” section in the Seller Dashboard. This option will show up when you hover over the product title
Mark one product listing as ‘in stock’ and the other as ‘out of stock’
Hover over the ‘in stock’ product listing in the “Manage Products” section and click “quick edit”
In the “Visibility” box, select ‘hidden’ and hit the ‘update’ button
You can then share the URL for the product listing with selected customers who will be able to purchase your product