Some decoration that's related to death in some way.. eg- A coffin ornament on a x-mas tree.

A surgery that removes his lower half and replaces it with some kind of anti gravity thruster

Your time.

Something to be enjoyed without hassle, time or effort, like e.g. a very good box with red wine?

Something to keep him warm during the colder weather seasons. Comfortable shoes/slippers?

Continence pads.

A collection of daily puzzles to keep one’s mind sharp ?

A nice bottle of whisky or port. A cosy jumper. A bird/bee house or a bid feeder or a bird bath. A hot chocolate maker. A cheese and chutney hamper. A magazine/chocolate/sock subscription. A tea pot/tea cosy. He’d probably prefer your company more than anything so take him out for lunch or dinner, or spend the afternoon there - distance and virus permitting of course.

I'm the wrong person to ask I was raised by wolves and the only gift I gave was rabbit pelts and shit

https://ibb.co/3k2gyWC

Wine or flowers.

Clothes