Sorry for your losses, that is really tough. I appreciate you sharing, it resonated with me. My mom's dad passed away two days ago and in the last two weeks before death a stroke destroyed his ability to speak. Nowhere near the level of locked in but terrible in its own way.
Death really is grim, I haven't had much exposure to it in my life up until losing two grandparents this year - holding my mother as she sobbed was heartbreaking.
I can't help but contrast the idyllic memories I have of my grandparents when I was young and the world was so bright and wonderful to the feelings of dread and sadness now. As if a layer of darkness has been laid over my perception of the world. It feels like hapiness and joy, things I used to find intrinsic to life, are now fleeting constructs that we build in spite of the inevitable. Maybe this is the difference between a youthful perception of the world and a mature one.