Will my speedrun be verified if it is done on a modified switch?

Modified no, modded yes

As long as you're not using any tools as you're doing the run so practice tool has to be disabled before the run

if you use mods in the run it will not be verified, but if you use mods in practice and disable it for the run you will be fine.

i think aslong as you dont have anything thas boost the ram to load thing faster your ok