I'm trying to make link to external website in Oro app, using navigation.yml file. I'm doing it with uri option like this:
test:
label: 'Test'
uri: 'https://external-resource.com/'
But it appends url to the domain of my website. How can I achieve linking to the external website?
You are using the right syntax. I've just tested the above example in the OroCommerce back-office and the storefront main menus and everything works. So the issue is most likely in the twig template, used for rendering the menu.
To find, what twig template is used for the menu, you can use the Oro Twig Inspector that already integrated into the OroCommerce application.
In the template, you should use the item.uri as is for the href, as it's done in the base menu template, used in Oro applications.