Problem getting flat-rate numbers into postage/shipping Product info

I’m doing a WordPress/WooCommerce site makeover for a small business that only has about a dozen specialty products for sale.

The client’s present system for Handling/Shipping charges (which he wants replicated) is having a set H/S fee for U.S. customers, a set H/S fee for Canadian customers, and a set H/S fee for international customers. (Plus, California residents pay 8.25% sales tax.)

WooCommerce seems to expect Product-page input that lists dimensions and weight, which it will then use to calculate shipping at Checkout.

How do I tell it, “No, at Checkout, for Product X, simply display one of these three pre-set options, depending on the customer’s address. Period” ?

Seems like a fairly basic matter, but I didn’t see any recent posts on the topic.

Thanks for any insights.

https://www.ads-software.com/plugins/woocommerce/