Yes there where many nationalities in the austro-hungarian empire including Germans. Who like most othere nations in the austro-hungarian empire proclaimed there own national state:
"Deutschösterreich" in the 1919 uprisings. It's weird from a modern perspectiv I know but german is what german speaking austrians called themselfes back than. The Word austira itselfe was tightly connected to the Habsburg dynastie, the house of austria. Keeping the name austria at all was up for debate at that point.
Sure there are Hungarian, Czech, Slovak, Slovenian and Burgenland Croat minorities even today. And the modern austrian nation which looks on the monarchy with some strange sence of nostalgia accepts them as austrians. But that is
after the war and the
"victim theory" had fundamentally changed austrian identity.