My husband is extremely messy

My husband has ADHD along with anxiety & gets depressive episodes. I also think he has signs of PTSD from childhood abuse.

He relapsed on hard drugs early 2018-2020 & hasn't been the same since. He has been sober for two years now & has gotten better in almost every other aspect of himself but still struggles with the m**h hoarding, tinkering, and excessive dirtiness. I cannot explain how bad he leaves things. Like if he need to take the fan vehicle to work, it'll come back trashed. He says "I'll clean it just give me time" and it never happens. He starts a project and abandons it the next day. He says he will do something but that "will do" it anywhere from a week to months later. Right now I have knives, scissors, tools, trash, boxes of stuff (doom piles basically..stuff that hasn't been touched in months) all over my yard. I say every day how sad it makes me and for him to please stop starting things he can't finish and to just clean up but it's like he mentally cannot handle what he has to do. Yesterday he was outside working on something completely random that didn't see to be done .I'm so tired of everything I have never being fixed, half projects and all of my stuff being trashed.

I don't know how to help him. Besides this, he is a loving husband and father. We get along really well and our best friends. He is responsible in every other area except for cleaning up after himself. It's so embarrassing I cry about it every day though.

Is there some kind of physiological help I could research or any advice I could use? I don't know how to support him. He knows it's messy and wrong and is a big source of shame for him and reminds him of his past every day. Idk what to do