The last troops to fight for Germany during World War II weren't German:
The 33. Waffen-Grenadier-Division der SS Charlemagne (französische Nr. 1) and Charlemagne Regiment are collective names used for units of French volunteers in the Wehrmacht and later Waffen-SS during World War II. From 7,340 at its peak in 1944, the strength of the division fell to just sixty men in May 1945.
They were arguably the last German unit to see action in a pitched battle during World War II, where they held central Berlin and the Führerbunker against the onslaught of Soviet infantry.