Nintendo explains the game cartridge known as Game-Key does not link data to a Nintendo account, allowing for easy transfer and resale of devices.

Previously, Nintendo revealed that the Nintendo Switch 2 will offer game developers the option to release games in cartridge form without game files, but only with Game-Key for game downloads. This allows for games with large file sizes to be supported. The lingering question remains: can these game cartridges be resold?

GameSpot inquired with Nintendo on this matter and received the response that Game-Keys will not be tied to Nintendo accounts or devices. The cartridges must be inserted to play the game.

In essence, this explanation concludes that game cartridges with only Game-Keys can be used on other devices or resold.

Source: GameSpot

TLDR: Nintendo Switch 2 will support games in cartridge form with Game-Key for downloads, which can be used on other devices or resold.