Not first-hand, but it would make sense for PCO and PMO to be informed of the intention to launch the app. Indeed, there was a community of deputy ministers and officials at all levels who were working together very intensively over that period of time: the Public Health Agency of Canada, Health Canada, Immigration, Transport, Global Affairs. All these people had an interest in the pandemic and what we were doing to manage it. They were meeting regularly and would have been informed of the intention to move from a paper-based process to an electronic process.
On November 17th, 2022. See this statement in context.