"Our cookware is fully American made us"
If this were a Chinese company, it would be easier to explain the fractured grammar, but according to the company's website, "Heritage Steel is a family-owned cookware manufacturer in Clarksville, TN." So, unless Heritage Steel hired a Chinese PR firm to write its U.S. promotional material, how did this happen?
Is it so difficult to distinguish "us" – which merriam-webster.com refers to as the "objective case of WE" – from "U.S." – as an abbreviation for the United States of America?
But you don't need either "us" or "U.S." in this case. Heritage Steel could have simply titled the email:
"Our cookware is fully American-made"
(Don't forget the hyphen!)
Alternatively, the email could have been titled:
"Our cookware is made right here, in the U.S.A."