Actually, the Luger is as American as apple pie. It was
originally designed by an American, Hugo Borchardt. who
tried to market it in the United States. No sale. So. being
enterprising, he sold the idea to a German firm where
George Luger came up with the Luger design as we know
Just marketing fluff trying to appeal to an American market.
Hugo Borchardt did emigrate to the United States and became an American citizen, but the C93 pistol was developed after he returned to Germany, while he worked at Ludwig Loewe & Company in Berlin. The C93 was a German pistol.
Also, saying Hugo Borchardt designed the Luger is like saying John Bowning designed the Glock.
The 1911 and Glock share the short-recoil system designed by John Browning (just as the Borchardt C93 and Luger share the Maxim toggle lock system, which was not designed by Borchart, but was used earlier on Maxim guns). But no one says that Glock pistols were designed by John Browning.
The fact is that Borchardt designed the pistol at Ludwig Loewe & Company in Berlin, and despite being a very forward thinking design, it was not a commercial success. Georg Luger (also an employee of Ludwig Loewe & Company - he did not "buy" the design from Borchardt) came along a few years later, took the basic Maxim toggle-lock system of the C93, and designed a completely new frame, lockwork, and cartridge. The end result was the Luger pistol.
Here's a website with a brief history of the C93 and Luger pistols.