Contact the USA pension office. They will send you forms to fill out. You will need to go to the US embassy to submit papers and legal documentation for your child (birth certificate etc proof that he was the father).
Your child is at least entitled to those benefits.
I am a Canadian who was in a similar situation with my son. American Father passed away.
If you are doubled vaxed no. There is random testing once you are in Canada. Make sure you download the app ArriveCan. It must be filled out before you arrive in Canada.