You need an ETA for Canada if you have a Vatican passport

Travelers need a travel authorization to visit Canada for Business or Tourism. Visa-exempt visitors entering Canada must obtain an Electronic Travel Authorization (eTA). Travelers can submit the eTA application online. Once the application is approved, travelers receive their eTA confirmation electronically. An eTA is electronically linked to a passport and valid for up to five years. If travelers receive a new passport, they must apply for a new eTA. A valid eTA is required to board the flight. If the eTA is expired or doesn’t match the traveler’s passport information, travelers will not be able to board their flight. Travelers who are permanent residents of Canada or the United States do not need an eTA. Please see the source for details.