Absolutely, thurg. Submarines travel secretly, unseen (they hope), and they go as far as their range permits. Their submarines went up the St Lawrence, ours went as far as Tokyo Bay. They put a few people ashore for espionage and sabotage purposes. We did the same on their shores with commandos and spies here and there.

None of that in any way resembles an invasion, or the capability of mounting an invasion.

Seaborne invasions aren't clandestine landings of a few men at night. They are a full frontal assault by a massive amphibious force involving infantry, armour, major air cover and a very large fleet.

This the Germans could not do to North America. Not even vaguely possible. They didn't have a big enough navy to do it. They had no aircraft carriers to provide air support, and the USA was much too far away for the Luftwaffe to take part in any such operation. Nor did the Japanese have the strength to invade the West Coast. No chance. They would have needed to move at least half a million men across the entire Pacific to do it with any hope of success. Their incursions in the Aleutian Islands were a sideshow, mostly occuring as a side effect of the botched Midway operation. They had sent minor forces up to the Aleutians to supposedly mislead and misdirect American forces in regards to the main attack on Midway. They were unaware that the Americans had broken their code and knew they were going to Midway. When the Midway operation failed utterly, the Japanese hung on to a couple of little islands in the Aleutians, mostly just because they were already there. It was a useless piece of real estate, but they figured it might tie down some American forces for awhile to keep a Japanese garrison or two active there, and it did that.

The only major power that Germany might have been able to invade amphibiously was the UK...given that the Channel is only a few miles wide. Still, it would have been very tough, because the British Navy had the German Navy outnumbered by about 8 to 1 or something like that.