Grandad means it when he says he needs nothing, so buy something that gets used up or a day out. Anything that needs shelf space starts at a disadvantage with a man who has spent decades clearing it.
There is a real difference between a dad who says he does not need anything and a grandad who says it. The second one usually means it, and has often spent years actively reducing the amount of stuff in the house.
That rules out most of the gift market, which is fine, because it points straight at what does work.
Consumable, or an occasion
Anything he uses up creates no obligation and takes no space. Good food, something to drink, something for the garden or the barbecue.
The alternative is an occasion rather than an object: a meal out, a tour, a class. It gives him something in the diary, which for a lot of retired grandads is worth more than the thing itself.
Skip the memorial-grade personalisation
Engraved keepsakes and "World’s Best Grandad" prints are bought far more often than they are wanted. They are difficult to display, awkward to remove, and impossible to pass on.
If you want the sentiment, write it. A letter costs nothing and outlasts the print.
