I don't think Monster Hunter would have had as big as an impact on hardware sales as Animal Crossing even without the lockdown boost (Japan maybe, but not worldwide) however it is definitely a system seller so should boost the numbers.
March-April-May are still pretty much guaranteed to be down YOY though if the weeks align... last year they were 4-4-5 weeks, I dont know how VGC determines which months are 5-weeks long so I think only chance of 2021 beating 2020 is if April is 5-weeks this time.
Come June we will be able to see better how well Switch is doing compared to last year, I suspect it will be down by ~ 500k-1million (but a better holiday period could mean similar sales for the full year)