For what it's worth for your peace of mind, by the time someone who's been diagnosed by a Psychiatric Physician as having dementia which in your grandmother's case would likely be 'vascular dementia' ...AND she is getting angry at everyone all the time, rest assured that she would not recognize you by name if you saw her face to face.
She would very likely remember everything you've stated in your post here which you've experienced in your childhood, but she would not remember you visiting her recently, even if you went to see her every single day. Her being able to remember her distant 'past' from 30 years ago is what often fools us into believing that they're getting better, when in fact they are progressively deteriorating with each passing day while maintaining a very predictable pattern of decline.
The reason for her remembering your childhood with her (assuming she remembers), is because that information is stored in her long-term memory, not her short-term memory. In a dementia patient, it is their short-term memory that is failing, not their long-term memory.
But even if she remembers her 'past' with you as a child, she wouldn't necessarily connect the dots to you being her grandchild, nor would she likely remember your name.
When anger starts to set in, it isn't because they are angry at those around them, it is because they are angry at what they can remember from their own lives which they hated and never resolved, which is often illustrated by them speaking angrily to people in their lives who they had issues with, but who are not even alive today.
What the dementia patient will do is choose anyone in the room to project their anger onto, even though it is the deceased person's face in their mind that they can see.
