Any good supplements for focus?

I haven’t been diagnosed with anything despite going to two therapists so I don’t have adhd or anything of that matter so adderall would be way too much for me not to mention it is prescription. I see so many supplements online for focus and it all seems like a scam to me. I’m just wondering if anyone has personally tried something specifically to help me focus/be motivated on my homework. I’m not gonna trust a company selling the product I need personal experiences. It could be a daily thing for the entire day or just to help for a few hours. I know motivation is mental but I think it would improve if the homework didn’t take hours to do because there is always something. I use caffeine when I do homework but it doesn’t really improve my focus. It improves a little bit not enough to make homework efficient. I am 18 so hopefully that broadens what I can use. I don’t have a med card so I can’t use cannabis. I also drive a lot so it wouldn’t be useful anyways