Nintendo has provided a detailed resource page on its website highlighting the backward compatibility of original Switch titles on the upcoming Switch 2 console.
The chart on the page indicates that most last-gen games will run without any issues on the Switch 2.
Even titles like Ring Fit Adventure, 1-2-Switch, and Labo kit assembly games are supported with original Joy-Cons or certain workarounds.
Nintendo is continuously working on improving compatibility with its publishing and developing partners before the console's release.