Given the current guidance states that COPR holders coming only to "finalize their applications but not settle in Canada yet" are not deemed essential travellers, you should apply for an extension/follow whatever other procedures are in place if you can't move to Canada now.
Although the detail of the CoPR extension has been published yet, it is almost guaranteed it will be extended for people who are unable to land due to the Covid travel restriction. Canadian government can't really punish applicants due to its own policy restriction.
