They've had pre-orders for the standard edition for Switch for weeks, but not Multiverse Edition on Switch (despite having Vita and PS4 Multiverse Editions listed for a while). I've been checking their website every few days to see if they'd carry the Switch version of Multiverse Edition, and sure enough they finally added it.
Not sure how limited in supply this will be, so pre-order while you can.
In related news, the Wii U physical copy is not being carried by any major retailers, but will be made available to buy online in limited supply. Details on that version will come at a later time.