Basically? No. There simply weren't Axis troops in Portugal.

Although Portugal was nominally neutral during the war, largely in part to the Anglo-Portugal Alliance, it did offer some aid to the Allies. Portugal was a popular exit point for European refugees evacuating from France and Germany to cross the ocean into either the UK or America. In 1943, Portugal leased land to the Allies to place air bases on, for easier access to mainland Europe, and later cut tungsten exports to Germany the next year. Because of this passive co-belligerency to Axis military forces, and because it was at the end of a long expanse of nominally anti-Axis Spanish territory, Axis troops had no reason to be in Portugal.

Although, there was a significant amount of international espionage in Portugal- Lisbon in particular- during the war. As the Portuguese authorities basically turned a blind eye towards espionage as long as it didn't reach into or interfere with state functions, Lisbon was a popular place for Allied and Axis intelligence agencies to obtain, pass along, and intercept information. Direct communication between Allied and Axis agencies, however, was fairly uncommon, or at least undocumented.

So, no, there weren't Wehrmacht soldiers having beers with American G.I.s, but there was at least some kind of contact with the opposing side in a high-level way.