IF the whole thing about Switch 2 using HOS like Switch 1 is true (I saw mentions of it here and there but no actual proof of it, aside from people saying that it looks the basically the same on some screenshots shown by nintendo) then there is a non-zero chance (but very, VERY low) that there may be a softmod.
Theoretically, homebrew devs may had found a software exploit on Switch 1, but they may had kept it a secret for a long while until Switch 2 releases... exactly for the possibility of it running the same OS. If the hac works on every new Switch 1 HOS update, then it may as well work on HOS on Switch 2. Releasing it as soon as it's found would make Nintendo patch it on Switch 1, and obviously, on upcoming Switch 2.
So,
IF such a theoretical exploit was found and is currently unreleased, Switch 2 could potentially have a day 1 hack.
EDIT: However, as apparently Switch 1 games are going to be ran through some emulation layer (as per
https://blog.ihaveahax.net/2025/04/06/lets-correct-some-nintendo-switch-2-misinformation/) the hardware differences may cause it to not work either way due to highly possible addressing differences.