Hi,
you are right in principle. But you can also use the Groups - negate feature, which would negate everything. So if you have a group for Germany only, and you apply the negation, it would filter all items for which this is not the case. This feature, however, has a large scope, as it can either be active for all groups or none.
You can find it under Groups -> Settings -> “Inverted”
Cheers
Simon