German can be an adjective. You can also use Germanic.
Germany is a proper noun, but it could be made an adjective by adding an ish to it.
West Germanic
"German" can function as both a noun and an adjective. As a noun, it refers to the language spoken in Germany and other regions, or to a person from Germany. As an adjective, it describes something related to Germany, such as culture, people, or products.
geduldig (adjective) Patient (noun)
cultural
The word German can be a proper noun or a proper adjective. The noun refers to someone in or from Germany (a German), or the language spoken there. *as a genealogy term, it does not use a capital G
The word "German" can function as both a noun and an adjective in English. As a noun, it refers to a person from Germany or the German language. As an adjective, it describes something or someone related to Germany or the German culture.
The proper adjective for Germany is German. The word German is also a demonym for a person from Germany, or for the primary language of Germany. Germanic is the proper adjective related to the German language.
The proper adjective for Switzerland is Swiss, as in 'a Swiss bank' or Swiss cheese. Helvetic and Helvetian are less common proper nouns for Switzerland, deriving from the country's Latin name.
Juicy is an adjective. A proper noun is the name of something like a person or a country e.g. Mary or Germany.
German will work, and in some references to very old roots in history or language, you will sometimes see Germanic.