I recall that the last time Canada considered new submarines (not counting the rusty, used Upholders), the Mulroney government wanted nuclear subs. The Reagan administration expended considerable political capital to get the nuclear technology-transfer approved, only for the Canadian government to throw the plan into the dumpster. Since the U.S. already thinks we're pretty feckless in defence matters, there's little chance of Canada being invited to joint AUKUS, at least as far as the nuclear submarine option is concerned...