I think it's more likely to have flopped because it's a $60k+ car with less range and barely faster charging than the (until recently) $20k Chevy bolt, and it's big appeal would be road trips that it can't competently handle. If they had sold it at a price competitive with its actual competition, e.g. other minivans, and/or if it had decent range it probably would have done better.

In Ontario, there is a 14 month waiting list for a Sienna. The only other option is the Chrysler Pacifica and people would rather wait a year than drive that turd.