Hi OP
I also get overwhelmed by a huge task of the whole house so I'm another one who breaks it down.
So I sit down and do whatever, usually mumsnet, or message my friends but it could be tv if you prefer. Then I think what one job I want to do first. It could be the washing...or if that feels too insurmountable then part of the washing. Maybe you are going to fold up any washing that is hanging up and put it away or is clean and dry in your basket. Then if you need to sit down again for 5 minutes before you tackle the next bit thats fine. But I usually find once I'm up and folding the washing away I may as well chuck a washing on. Or pick something up and take it to the room it goes in.
It's definitely helped me to get my house much more in order. I don't have ADHD but have ND kids and have always wondered if I may also have it or certainly have traits of it. This way of working (not just with housework but anything that needs organising and doing) really helps me. I feel a lot less overwhelmed these days.
I used to worry it made me look or seem lazy, but it's not about the sitting down to rest or because I'm lazy, it gives me a brain break and I can then think clearly for the next task.
I am also a list fiend. I use my notes on my phone and the tick box function. Think what 3 main jobs you would like done today, or two or even one. Break that job down into manageable chunks (so main job maybe washing - 1. Fold up dry washing and put away. 2. Put washing on. 3. Hang washing out. 4. Put any dirty washing lying around ready for later or tomorrow. Tick them off as you go and you'll get a little dopamine hit.
And saying that, I'm going to go and fold up my dry washing and put away. Follow my own advice. 😅
Good luck. I'll be back if you want to keep checking in? Happy to pop in and cheer each other on a bit.