The US didn’t HAVE any heavy armor. The M26 Pershing tank didn’t make it to the battlefield until February of 1945. The most advanced weapon available was the M4 Sherman. A number of them were converted for amphibious operations, but none survived the swim to the beach.
Here's a pic of the antitank barriers. Rows of these extended out into the water, making it nigh-impossible to drop vehicles in the surf.
There were a handful of Shermans on Omaha Beach. Most sank in the choppy water.