US only requires Antigen test to return, so not vaccinated you need a negative antigen tested within 1 day of your flight. If vaccinated, then it maybe 3 days before your flight.
Apparently there is a "home kit" for Canadians that give PCR like results in a few hours. It is an RT-LAMP test... whatever that means... but results are similar to PCR and much more accurate than a Antigen test....