I tried a few Nootropics from Gorilla Mind (they sell great shit), specifically the Gorilla Mind nootropic for focus. Unfortunately for me, the formula didn't jive with my ADHD. It had a different chemical reaction in my brain. It did NOT help me focus better. It rat fucked my sleep, made me feel a bit disconnected and made it harder for me to stay grounded.
The product is just fine and it seems to work for many people. so no shade on them at all. It just isn't formulated for ADHD. I have found that (as
@Morell stated) a clean diet is best.
That said, most of those focus or energy supplements are formulated for the Neurotypical brain. Neurodivergent brains are wired differently, so the results will be either mildly or wildly different than advertised. You may be able to find something that works for you, but it will be mostly trial and error. Not saying it cannot be done, just harder due to different brain wiring.
Also, if you are on meds for ADHD (and I chose not to take take them) talk to your Doc before taking other shit as it will impact you.
Learning how my ADHD patterns itself, how to live with it and use it to my benefit. I choose not to take chemicals, that's just my personal choice.
Since you were just diagnosed, maybe get used to the idea before cramming chemicals into your system and jacking your baseline all to hell.
YMMV.