The Germans had the largest flying amphibian plane that flew. I met the American pilot, believe his name was George Drew, who shot it up at its dock.
He was also the only American pilot (P-47’s) to shoot down/destroy two ME262 jets. He came in behind one taking off, downed it and then destroyed one on the ground.
If you have seen the film of an American plane blowing up a German train and flying through the blast, that’s him. Took all the paint off his P47’s underbody.
Don’t believe that the Spruce Goose ever got off the water. There was a very big congressional investigation into its contract and mismanagement. However, Howard Hughes escaped serious penalties for this fiasco.
Don't hold me to it but I think the SG managed to get into the air for at least a few seconds and a few feet.