Hi and welcome to the forum
@John Mcfarlan
Have you been in contact with any of the local charities or similar organisations that may deal with people with dementia (PWD)?
In my area Age Uk and separately a local church have "Dementia Cafes" or "Forget-me-Not cafe" where a PWD can go with their carer for a 2 hour session for contact with others, jogsaws, quiz, music and singing, old photos, and memory cards to stimulate memories and conversation etc. Usually you have to register with them as some have limited numbers of places, or even waiting lists. A different church runs a weekly session called Memory Singers with old songs etc.
Dementia UK - look on their website - have various activities including appropriate exercises for fitness for all abilities or none
The Alzheimer's Society has a booklet or online of activities for PWD
Many areas have a "Mens Shed" or ladies' equivalent or day centres with activities (and including lunch, hair washing, etc) (for a charge)
So you see, if you look, I'm sure you'll find activities suitable for your OH. Do try these, because the time during which a PWD can enjoy these activities is limited.
Best wishes