Sounds like you are taking the right steps! My SO and I are currently in the process of registration for adoption, and we're participating in required courses to learn more about how to tackle raising children with "special needs", emotionally or physically.
A big chunk of what we're focusing on in the courses are
1) seek knowledge, support AND professional help early on,
2) focus on what each individual child needs, not societal or cultural expectations, and
3) turn-taking: OBSERVE (listen, see, body language, reflect etc.), TAKE INITIATIVE (ask, propose solutions, take action), OBSERVE and PARTICIPATE (let the child take the lead and propose solutions).
All in all, it's about looking at every possible situation from the child's perspective, with the child's past experiences and internal processing as a guideline for what its actions are. A lot of parents forget this because society is so focused on predetermined expectations.
With ADHD for example, a lot of children experience constant negative feedback (sit still!, stay quiet!, focus!, sleep!, remember!, just concentrate!) that they don't have the resources to process in a healthy way *on their own*. Our brains are differently wired, and we often lack the mental capacity to do what society expects from us.
In addition, our brain's dysfunction of the dopaminergic system means that we don't respond well to positive feedback or actions either (dopamine release, which we lack, is a key ingredient in learning and motivation for daily tasks as well). That's one of the reasons people with ADHD often go for short-term gains (stimuli, candy, PC gaming, drugs etc.), rather than long-term benefits (exercise, school work, household chores etc.). That's also why we have difficulty with emotional regulation, often resulting in tantrums and the development of depression etc.
Or as I like to put it; we have no clue of what we're doing or why we're doing it. We have "normal" intelligence, so we know how it could be done better, but we don't know why we just can't do it. It's a continuous internal battle with ourselves.
This also means that many children with ADHD grow up in what they perceive as an emotionally hostile environment, even though they have a "normal" or "healthy" childhood perceived by others.
There are a lot of different free courses online that can give you some daily tips and tricks, for example, https://www.coursera.org/learn/adhd-treatment
I wish you the best, and thanks for seeking advice to do the best for your child! He's lucky to have a parent like you!