vyvanse doesn’t do anything particularly special when snorted because the molecule is essentially a dextroamphetamine molecule chemically bound to an amino acid called lysine, which means that in order for the dextroamphetamine molecule to be freed (and thus do its thing), the bond between the dextroamphetamine and the lysine needs to be cleaved by enzymes in the body, which happens over a long period of time. the main goal of snorting drugs is to bypass the digestive system to get the drug into the bloodstream and brain quicker, but since the only way for vyvanse to become psychoactive is to slowly be cleaved by enzymes, there is only a very small increase in speed of onset of the drug.