The icons you linked are available within the Backoffice without having to wrap them in anything. You’ll have to type the name into <uui-icon name=”X”></uui-icon> – that should work.
The Backoffice does not really export its icons outside of the Backoffice if that is what you meant. Perhaps you could give a little more info on what you are trying to achieve.
I’m building a custom section from a package, with a custom dashboard. On the dashboard, I want to add an icon, inside an UmbLitElement’s render method.
But I tried your approach and it’s working!
I had to use the actual names (with the “icon-” prefix) in case of non-essential icons.