How did nationalism in austria affect german expansion before world war ii?

It resulted in little Austrian opposition to the German annexation of Austria

Hitler was determined to annul the remaining military and territorial dispositions of the Treaty of Versailles (the post-World War I peace agreement) and to include the German ethnicity in the Reich as a step towards the creation of a German empire in Europe.

After a prolonged period of intense propaganda inside Austria, the German troops entered the country on March 12, 1938, and received the enthusiastic support of the majority of the population. Austria was incorporated into Germany the next day. In April, this German annexation was retroactively approved in a plebiscite that was manipulated to indicate that approximately 99 percent of the Austrian population wanted the union (known as the Anschluss) with Germany. In the plebiscite, neither Jews nor Roma were allowed to vote (gypsies).