Our family had a close friend that apparently, during the height of COVID, experienced significant mental decline. She decided, in close consultation with her children, to stop eating and drinking when she was still clear enough of mind to do so--she was in her late 70s. They shared it during a worship service, and then she actually had the blessing of hearing others share their love and memories with her--when she was still alive to hear them. How many of us wish we could be at our own memorial? She kinda was.
Afterwards, even though she had not seen me in over five years, she came up to me, gave me a big hug, and then proceeded to ask about my DD (who was not with us, but whom she had seen with my mother numerous times in more recent years.) She declared that she had been so looking forward to eating one of my mother's muffins (which she brings with her to Meeting,) and then remembered that she wasn't supposed to be eating or drinking! She told me this with a huge laugh and smile on her face. The whole thing was really quite beautiful. It took her about a week post-decision to die peacefully, in her own bed, in her own house, surrounded by all of her children and grandchildren.
And then there was another beautiful memorial service a few weeks afterwards. Sharing this story, since it's been mentioned in this thread. Not eating or drinking, combined with a DNR, means you don't need to live in an assisted-suicide state, or rely on the participation of another person, to die on your own terms.
My mother was very moved by the whole thing. Even though she is in a class A CCRC, I think she may go this route if there is any significant mental decline or dementia, or the Parkinson's gets to a point where she can no longer do any of the things that she most enjoys doing. She is no where near that stage yet, and may never be, since slowly-progressing Parkinson's doesn't really "speed up."