No, it is not possible to activate a Prepaid SIM until you are able to access the Canadian cellular network.
My suggestion is on your arrival, find a point of sale, likely at a shopping mall, and spend half an hour getting your prepaid account set up. At the end of your trip, you just abandon your prepaid, and it will cancel in 90 days. You don’t need any ID to buy prepaid in Canada, and your credit card will be a satisfactory method of payment.
What is your point of entry to Canada?
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