How can I create a product listing that only one customer can access/checkout?

Site URL: https://www.timesmith.co.uk/shop

It's common in my sector to negotiate product details for customer's individual tastes and then create a product listing in the e-shop, which only that person can access and purchase. One way is by making the product listing only accessible with a password or by an individual link/code that you only give to that customer. Is this possible in Squarespace Commerce? If so, how do I do this? Thank you!

Yes, but you'll need to add a new Store page for each customer, because the password can only be applied at the Store level, not an individual product within it.