Not to make light of your problems, but I'm envious that you are looking for activities for your 92 year old dad, with dementia! My mam is only 75 and is way beyond being able to entertain herself with any useful (or even non-useful) activity now.
All she does is pace around the house, pulling furniture out, de-making the bed, picking things up and putting them in odd places, and has a fascination with cushions and other soft furnishings. Over and over, hour after hour.
Oh how I'd love it if she could do a bit of dusting, polishing, hoovering, tidying, anything. It would be lovely to see her doing something like that, especially as she was so very houseproud in the past and everything was always immaculate.
I know you have your own set of difficulties and I'm not trivialising them, honestly, but oh I do wish ...