How about a subscription to a documentary streaming service such as CuriosityStream or DocPlay? You could also look for DVDs or Blu-rays of his favorite documentaries, or perhaps a book about his favorite documentarian or a topic covered in a documentary he enjoys. Another idea is to create a "documentary night" gift basket with snacks and drinks included, where you could watch one of his favorite documentaries together.
Or you can get him a star map with the date when he was born.
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.