It’s going to be hard for her partner, friends, and family, but it would be so much worse and so traumatic if she didn’t have help or had to hide the desires until she took her own life regardless of the laws.
I’m not sure that’s true. Losing someone to suicide is in itself quite traumatic. One relief many people have is when they wrap their head around how a self destructive impulse in the heat of an especially devastating moment could have led to it. But living with the fact that your daughter/wife/sister/friend very consciously decided she would rather be dead than to share in this life with you - that’s tough. It’s not unusual with relatives of suicide victims to struggle with feelings of intense anger towards the person they lost, which in turn can lead to feelings of guilt and shame. It’s hard to work through something like that. And I don’t think it gets any easier if the circumstances are as emphasised as in this case.
I think there are very valid use cases for assisted suicide. Personally I doubt that depression is one of them, because suicidality is such an inextricable part of the disorder itself. At the end of the day this is a suicide, just with extra steps and a stamp of approval by a national agency. The people surviving her will not only have to work through the fact of her suicide but process the official approval as well.
The only advantage to a “regular” suicide I can think of is avoiding the trauma of the person finding you. (Although there are probably ways around that anyway.) But I guess she has her reasons to have chosen this specific method and setting.