I think it depend on the where you enter. I have used the ArriveCAN declaration a few times to enter YVR - I believe it was mandatory during Covid - and I've found it of limited value. There are no express lanes that I saw - you go the the kiosks along with everyone else but you save maybe 30 seconds not having to enter your declaration again. But after you get the receipt you line up with everyone else in one long line. So there Nexus might be faster and worth having.