this has already been ruled unconstitutional repeatedly and i would stand in solidarity with businesses that defy this order and stay open.
i would encourage somebody to challenge this, legally.
https://montrealgazette.com/news/quebec/most-quebec-stores-will-be-closed-on-sundays-as-coronavirus-cases-mount/wcm/ca148c14-0557-4145-b5ff-d173473baef8/