I am shipping to one country (Canada) but want to be able to list the country of manufacture for each good for sale.
I can set the allow countries list and set up shipping so only rates to Canada are shown, but any allowed country can be selected on checkout. Even though it causes a message to appear.
How can I just show Canada as a shipping allowed to country on checkout?
There is a setting in store configuration general which allows you to select allowed countries. This will restrict the country list in every dropdown on the site though. Is that desired? Or are you looking to only limit the shipping dropdown? Is so, you'll probably need a custom extension/code to do that.
It should be possible to do.
You'll need to do it for all shipping methods your website uses.