Nintendo has long maintained that most games will be compatible between the original and upgraded Switch consoles, but the exact details of this compatibility have been unclear. Recently, an FAQ from Marvelous, the developer of Rune Factory: Guardians of Azuma, revealed some surprising information about the Switch 2’s cartridge compatibility with the original console.
According to the FAQ, at least some Nintendo Switch 2 physical cartridges will be compatible with the Nintendo Switch 1. The FAQ states that these cartridges contain the base game and upgrade pack for the Nintendo Switch 2 Edition, allowing users to insert them into either the Switch or Switch 2 consoles and launch the correct version of the game.
However, there are some caveats to this compatibility. Some games may have exclusive upgrades only available on the Switch 2, while others may be included in physical cartridges that include both versions. Additionally, some packaged Nintendo Switch 2 games may not actually contain the game itself but rather a download key for later use.
Nintendo has been vague about which games will be compatible with the Switch 1 and which will not. The company’s hesitation to clarify this point has left many users confused. IGN reached out to Nintendo for comment on the matter, but as of now, no further information is available.
Source: https://www.ign.com/articles/rune-factory-guardians-of-azuma-faq-suggests-some-physical-switch-2-cartridges-will-be-playable-on-switch-1