Following the news yesterday that Bioshock Collection will require a 31 GB download on Switch, we now know that the XCOM 2 Collection will require a 21 GB download and the Borderlands Collection will require a whopping 42GB download, both for the physical versions.
In the case of Borderlands, the cartridge only contains Borderlands: Game of the Year Edition, with the others coming as download codes for Borderlands 2 and Borderlands: The Pre-Sequel.
With XCOM, this is presumably for the expansions.
Source: 2K Store