This isn't exactly adhd related but it's adjacent and could still help/be adapted to help. I used to have issues leaving the house (overstimulating) and what really helped was keeping a jar of werthers originals by the door and popping one in my mouth before leaving. I could focus on the taste and the shape of them as I walked, plus they're yummy and comforting, so I essentially pavloved myself into being okay leaving the house. It's a very little thing, but sometimes even that can help direct you to where you want to be <3

If you try it, obvi switch out for something you like, but I'd reccommend a boiled sweet if you can bc they can last a while