I agree on phone usage restriction apps. You can also extend the usage as a reward for achieving things which would work as an external motivation that ADHD people need. I also agree with other people that it won't even be close to solving ADHD problems, people were just arguing with you about different thing because they thought that you have the same perception of ADHD as the top level comment.

If you're aware of how adhd works then you of all people should know that "throw your phone in the toilet" is shite advice that only someone who doesn't know how adhd works would give. If you have adhd then you should know better than that.