Topic: Cartridge Data to Downloaded Game

Hello, internet!
My friend recently wanted this new game that I have. I was planning on lending him the cartridge for a while so he can see if he likes it. Nowadays he only buys the digital copy, so I was wondering if he could transfer the progress accumulated on the cart to his downloaded version.

Yes, Nintendo has an app that lets you transfer save data from a cartridge to a digital version of the same game.

Just download it from the eShop.

@Morpheel
Thank you very much for your help.

That's correct for 3DS, but if you're talking about Switch then you won't even have to do that. Switch games save their data to the console itself, so once your friend downloads the game then his save file will still be there, no need to do anything!

One important note: both the physical and the digital need to be the same 'build' (e.g. both special version of a game or not) for the savegames to be the same file.