Is there an Dzogchen monastery in Canada with a accomplished lineage?
I'm not completely sure if this monastery is a Dzogchen monastery, but you can try the Thrangu Monastery in British Columbia, Canada.
This monastery belongs to the Kagyu lineage.
You can find a list of teachers here.
This wikipedia page on Thrangu Rinpoche states that he trained Dzogchen Ponlop Rinpoche.