I believe that Germany never did use a guillotine. They used an axe man and the victim was placed on his back.
There were a few people they executed in the manner you describe because they were especially upset with them and wanted to make the experience particularly horrifying, but the vast majority of beheadings took place by guillotine.
More people were executed in Germany by guillotine in total than were executed in France by guillotine during the French Revolution. The East Germans continued to use it.
In the case of the people executed for the attempted assassination of Hitler, they used piano wire to hang them.
Probably used the one pictured in this article: https://www.dailymail.co.uk/news/article-2538973/How-Nazis-slaughtered-16-000-people-guillotine-Found-Munich-cellar-death-machine-reveals-forgotten-horror.html