Well, there was Rune Factory: Guardians of Azuma---although that also had a Switch 1 version launching at the same time. And in Japan, you also had Shine Post! Be Your Idol and Survival Kids from Konami.
Rune Factory: Guardians of Azuma was actually the highest selling third-party Switch 2 game during launch week in Japan, with 10,877 physical copies sold. But I guess that's quite low when considering the hardware itself moved 947,931 units.
This week's sales chart doesn't have any third-party Switch 2 games in the top 10, meaning whichever games make the top 30 sold less than 4,209 units in week two.
Comparing to Switch 1, which opened at 329,152 hardware sales, Media Create Sales place the highest selling launch third-party games as Super Bomberman R at 36,623 units, Dragon Quest Heroes I & II (a port) at 25,606 units, then Puyo Puyo Tetris (a port) at 12,854 units. Week two for those titles were as follows: Super Bomberman R: 8,550; Dragon Quest Heroes I & II: 7,206; Puyo Puyo Tetris: 4,469.