How about a cryptocurrency hardware wallet? This could be a perfect gift for your grandpa since it will help him to secure his cryptocurrencies and protect them from cyber attacks. You can choose from a variety of popular hardware wallets such as Ledger Nano S, Trezor, KeepKey, and more. Additionally, you could consider gifting him a guidebook or online course on crypto trading to help him stay up-to-date with the latest trends and strategies. Another idea could be purchasing him some cryptocurrencies he doesn't own yet to add to his portfolio, but make sure to research the best options first based on his interests and goals.
Or you can get him a star map with an important date you share.
Under Lucky Stars is a unique and innovative star map company based in Barcelona, Spain, specializing in the creation of personalized star maps that capture the celestial arrangement of stars at a specific moment in time, such as a person's birth, wedding, or any other significant event.
By using advanced astronomical algorithms and data from leading institutions, the company produces highly accurate, visually stunning maps that make for perfect gifts or cherished keepsakes.