Just to be clear: Elizabeth is (to us) Queen of Canada, and other (lesser) possessions where she also holds titles :)
Since the patriation of our constitution in 1982, the PM’s office has been the central power officially, deriving the office’s power from our Charter of Rights and Freedoms. The Queen and her apparatus are figureheads without real power.
From Wikipedia (which seems to be concise and accurate): "executive authority remains vested in the Crown and is only entrusted by the sovereign to the government on behalf of the people."
Well, yes and no: it would be an extraordinary event indeed were the crown or its representative, the GG, to defy the “advice” of the government.
For example, the last time that happened ([1]), the laws of ALL commonwealth countries were effectively changed to grant them greater autonomy and sovereignty through the Balfour Declaration and The Statutes of Westminster, which more clearly articulated that the government’s “advice” to the Crown is to be acted upon, not merely taken into consideration.
Were the GG or The Crown to attempt to wield executive power contrary to or outside that advice, the result would in all likelihood be an immediate appeal to the Supreme Court, which would, in all likelihood, side with the government, and not with the GG/Crown.
As it is, having executive power rest with the GG/Crown means that there is continuity in executive power, even during elections (the current PM and other ministers remain in their posts until they resign; they resign just before their replacements are sworn in).
Since the patriation of our constitution in 1982, the PM’s office has been the central power officially, deriving the office’s power from our Charter of Rights and Freedoms. The Queen and her apparatus are figureheads without real power.