Travel to Z

I feel your pain. We are booked on a flight out of Toronto on January 9th for two weeks.
As most Canadians who are considering going, we are double vaxed and boosted. As you mentioned, the biggest problem is getting home should we test positive for the virus, most likely not having any symptoms. If I understand correctly what you have written, you seem a little confused about the going home procedure. You will not be getting on a plane without a negative PCR test and upon arrival in Canada you MAY be asked to submit to another test. You immediately continue to your home where you quarantine until you receive confirmation of a negative test. This usually takes 2 -3 days. They are talking about testing everybody upon arrival at some point but have not yet done so. Should there be a cancellation of all flights to Mexico like what happened before, the airline that you flew with will be sending some planes to pick you up, asap.

We have purchased our KN95 masks which I understand work extremely well.

We have also purchased a membership in Covac Global travel services which guarantees you Covid-19 evacuation and repatriation with just a positive test and one symptom even if it is just a headache or tiredness. It is expensive but we would lose far more money not going because we too would lose all our money paid for our accommodations. It is not an option for us to stay another two weeks.

If Air Canada cancels our flight then it is what it is.
We will have to accept our fate...