I think that the thing about adhd and reward is that it is entirely up to how mentally difficult the task is and almost completely disconnected from the actual task. The irony is that the simpler a task is, the more mentally complicated it gets as you avoid it since you start recognizing the absurdity of your struggle compared to the task, and this mental anguish results in a ridiculous sense of achievment once the task is completed.

I have avoided the dishes for a week, I did half of them and felt so good about it that it actually made me excited, just because all week I struggled so much with it that essentially the achievement was about winning this mental fight that was literally hurting me all week.

In a way the task itself is just a physical indicator that you got through the mental hardship