There are many places, depending on what it is waiting on and how long they expect the wait to be. When there are a large number of trucks waiting, like early in the model year, for somethign like a software update they will even ship them to other Stellantis plants like the Toledo Ohio plant, Nitro yard, etc. they will get the update performed there and then be shipped from there to the dealer.
So, without knowing why it was sent to storage there is no good way to know where. Your dealer would be the best chance of getting additional information.