I heard that during WW2 Canada offered the United States an alliance against Nazi Germany and to defend North America and forget about Europe, is this true?

I've never heard anything like this.

Canada declared war on September 10th. So any deal with the USA would have had to have done very quickly and very secretly and ultimately unsuccessfully.

Later initiatives regarding continental defense such as the 1st Special Service Force and the Alcan highway followed once the USA was in the war.