I have adhd so understand how difficult it can be to tear oneself from one's phone!
Swap it for a dumb phone - she can keep in touch with people but it removes the addictive element. Or if you really don't think you can do this, confiscate it for 2 hours a day so that she has to find a way to keep herself occupied - no screens allowed.
She'll complain like crazy at first that she's bored but we all have to learn to be bored and boredom is good for mental health, it leads to creativity so she'll start picking up stuff to do.
If she enjoys the gym but only goes with her friends get her personal training sessions. I can't do the gym on my own, I need some structure so fitness class or pt keeps me motivated (and I can't see her wanting to do fitness classes alone!).
Rather than overwhelming her with choices, give her a limited number to choose from in screen-free time, 3 is fine. If she refuses to do any of them, she can swap one from one she will do but it has to be screen free.
There are lots of books now about living with & managing adhd in girls and women that you should both read (not all of them lol). Studies suggest people with adhd have a dopamine deficiency making them vulnerable to junk food and junk for the brain (social media) because its designed to hit our happy hormones hard & fast. Replacing these with healthy options means we can manage the condition, stimulate and soothe our minds.
Hobbies are good, yes, but so is meditation and mindfulness.
The pomodoro method is great for short bursts of productivity. 20 minutes of tidying is all I can ever manage but you can get a fair bit done in that time, even with distractions. Doing it to favourite music helps. Pomodoro apps available.