Your points are well taken, Canada’s action early would be limited to mopping up the Atlantic of German subs (if they don’t lose what would become their sub and transport the first turn). They’d need a basic autonomy NO to pump their income and maybe they could get a reduced version of the UK’s no German subs bonus.
While they couldn’t do much once they land in UK or northern Africa they could open a few new angles going after Italy (would combine the turn with ANZAC’s). But I fear Canada’s best use would simply be to pump air units to UK/Russia from Quebec.