I am a geriatric care professional but I was a caregiver once, too
That's one of the things I learned as a caregiver to my father. He had Alzheimer's disease. Fortunately I was in graduate school at the time, and my graduate school required that I have 50 hours of psychotherapy. That 50 hours turned into several years of psychotherapy, from which I learned a lot.
Between the experience of helping my father and the experience of being in psychotherapy, just seeing what evolves, holding the tension of the not knowing, is one of the skills that I developed. Of course, some people look at me and think I'm not doing anything. What they do not realize is that waiting is an action. As John Lennon supposedly said, "Life is what happens to you while you are off doing other things."
I also learned that every person with dementia has a code. If you know the key to the code, you can engage with them comfortably and reliably. If you heard my dad and me talk, you'd think we were two crazy people. It wasn't the words that mattered. It was the tone. It was the feeling. I learned that people do not communicate with only words. I learned that people communicate by everything else: the tone, the enthusiasm at the first contact, the comfort with silence.
Enough rambling for now. I wish you well on your journey. Hope to see you again.