The Switch 2 is backwards compatible with Switch games, but it uses emulation to run those older titles, so it isn't playing these games natively. It works for the most part—Nintendo says virtually all first-party Switch 1 games can run on Switch 2 without issue,

That being said, Nintendo has taken it upon itself to test the many apps and games present on the original Switch ahead of the Switch 2 launch, and this aims to help players discern which they need to pour their efforts into and which not to.