https://www.gamespot.com/articles/super-mario-odyssey-file-size-revealed/1100-6453414/

The file size for the hugely anticipated Nintendo Switch game Super Mario Odyssey has been revealed--and it's not as big as you might expect. According to Nintendo Everything, the file size is only 5.7 GB for the digital version.

This is according to a post on Nintendo's Japanese store. By comparison, other first-party games on Switch are also pretty small, with Arms coming in at 2.2 GB and Splatoon 2 at 3.1 GB.