Your husband here.
Well, not literally. I am a husband to someone else, but share some characteristics of your husband. I too have ADHD diagnosis, maybe a bit different from your husband’s.
First let me comment briefly a gap between the address and the message of your question.
From what I can read in your message I could never say you are an A$$. You support him and cope with him. He can be eternally grateful for this. And should be.
ADHD men can be easily tagged as lazy, weak, drunk a$$holes, as less men, as less people and abandoned in their misery as worthless. Therefore as long as you stay and cope with him, you cannot be an a$$.
There is one thing which came into my focus about his “love of video games” and you and he should maybe think about. He is a man. And many men will sometimes in their lives have an issue with dopamine levels. Some of us more, some less. Some for a longer time, some for shorter. But this comes almost by design of males. It is just like many women have issues with serotonin. And dopamine issues can be treated with novelties which are delivered by achieved levels, badges, wins in video games. Videogame self-treatment is maybe even the least harmful one. Self treatment with alcohol could be much more dangerous. Or novelty seeking could be way more destructive if he would flirt with other women.
Restraining him from handhelds is maybe not optimal, but it is ok if he see it as HIS goal. You should not push this on him.
If he see it as a way to make him better functioning, it could be very good. It could also be very good for his self esteem if he see something as promising idea as something what would make him a better functioning men, a better person, then work on this (with your support) and then win some wins on this project.
I experienced something like this with morning routines years ago when I had no idea yet that ADHD is my problem. My mornings before were pure confusion and procrastinating until the “house was on fire” and all I was able to do was throw something on me and in me and escape from home for job or whatever. Then I realized this is no way to start a day. I made a list of all things I have to do before I leave. Then I measure time required for each of them. I observed what was the optimal sequence for all of them. And then I tried for a few days and failed. Then again and again and again… And after a few years of ups and downs I have a firm routine which makes me feel good about myself. I to can accomplish something what looks like natural for my wife and many others.
Wish you both all the best.