Not medical advice but IIRC, Vyvanse is essentially the name-brand product with an extra methyl group stuck on. Your pancreas produces an enzyme called Trypsin that breaks off that methyl group, and turns it into the active ingredient. It's considered an extended release because the enzyme's availability is limited in your body.

Trypsin is not exactly a common supplement, but you might consider looking into which kinds of foods can inhibit or encourage its production. Grains and cereals will probably inhibit it, unfortunately.