I also have ADHD, I think you're right in that the common assertion that people with ADHD always have short attention spans is really not correct. If anything, I hyper focus on things so much that sometimes I burn myself out! In that sense the problem isn't really short attention span but a problem of balancing my attention across everything I'm doing instead of just one single thing.
It can be extra difficult for me as I have a wife and 2 kids and a 9-5 job while also trying to make games as well as all the other hobbies I have (TV/Movies, books, Games, TTRPGs). There's not enough time in the day!
I wrote this in one of my devlogs, but I think I've been more successful this time around in learning gamedev because I'm not thinking too far ahead and just worrying about it one game at a time. Making a living doing this would be great, but first and foremost I want to be proud of the game that I made and make sure that I learn something new with every game. Whether it becomes successful or not.
Looking forward to seeing more of Abyssonance.