For various reasons Mum can't use her oven now and loads of people have suggested an air fryer but I can't even begin to think how we would teach her to use an entirely new gadget
You wouldn't be able to, you're right.
A friend of mine had a lift installed at her DM's because of her mother's mobility problems. It obviously cost thousands of pounds.
Her mother was highly suspicious of the lift and refused point blank to get into it. She couldn't remember what it was for, or why it was in her house.
Another friend had a shower installed for her DM.
It was only ever used by the live-in carers.