Curious about L-theanine

Does anyone have experience with supplementing L-theanine while on Vyvanse (or similar ADHD medication)? Do you find that the effects of it to mitigate the negative effects of caffeine by reducing anxiety, blood pressure, etc. and enhance the positive aspects like attention translate to amphetamines? I oftentimes take caffeine in combination with my 50mg Vyvanse but I find this to be physically unpleasant and I don’t know that it actually helps me cognitively in any way, so I’d like to try it with L-theanine and perhaps just Vyvanse and L-theanine on their own.