You know the person. They buy things themselves when they want them. They have good taste. They don't have a list. When you ask, they say 'I don't need anything' — and they mean it.
The answer is not to give them another thing. The answer is to give them something that can't be bought.
What can't be bought
Your specific attention. A record of what you've noticed about them, what you appreciate, what you've been meaning to say.
People who have everything are often still waiting for someone to just say the thing. The 'I see what you do and I want you to know it registers' thing. The stuff that doesn't fit in a cart.
Ideas that work
A personalized page with your message, your specific memories, and your photos together — something made only for them, that exists nowhere else.
A planned experience you'll do together — not a gift card, but an actual plan. 'I booked the thing we always talk about' is very different from 'here's a voucher.'
A donation to something that matters to them, with a handwritten explanation of why you chose it.
A letter. Not a card with a printed message, an actual letter. The person who has everything almost certainly doesn't have that.