Since we're having an impromptu ADHD club forming in this thread - I totally feel you. I've had too many ideas like this one, even some prototypes over the years.

There are many tricks to stay focused, particularly when there are no stakeholders but you. Try a body double, someone to keep you in check - you can also return the favor, like working from the same room, or just coming to their home to watch them clean while you do your stuff.

When you do get hyperfixated on something - that can be a very productive period, until you crash. Again, bring in a friend. Not to get back to it - just to make sure you're still eating. Don't push yourself to either side, find your own balance around it - I've picked up many hobbies where I've slowed down, but maintained interest over the years, decades.

Look for buddies in your local neurodivergent group, there's usually one somewhere near you. (Even here on HN, it turns out.)

Yeah, I've tended to be more successful at things when my partner is keeping me in check, but she doesn't live with me so that's not very often :P We might end up with a house together in the not too distant future though