Vitamin Connection makes use of pretty much everything the Switch has to offer, which doesn't make a port to other platforms impossible, but a ton of retooling would have to be done. As of right now, Vitamin Connection is exclusive to Switch, and it's not going anywhere else. Why did WayForward decide to do this? Director James Montagna explained in a Comicbook.com interview.
This isn’t a very deep answer, but... I said, “I want to make a game just for Switch!” and then we assembled a crew and made it! Another factor that might answer the question is that I think the development of Vitamin Connection was, more than anything else, motivated by a burst of creativity wanting to be expressed. And in the end, I feel embracing that creativity often leads to very successful business anyway. WayForward’s track record of original titles stands as an indicator of this.