If I understand what you want correctly: the Firefox multi account container extension (is that the default one?) allows to "manage containers" and by clicking

If I understand what you want correctly: the Firefox multi account container extension (is that the default one?) allows to "manage containers" and by clicking on the one you want you can select "limit to designated sites" so you can, from a container, click a non containerized link and get that link opened in the default/different container