I would offer ear plugs and electrolytes, the ear plugs can help block the engine sounds for a peaceful sleep and the electrolytes help you to hit the ground running!
Luxury brand luggage (set) is always a good move😍
My girlfriend offered me a cashmere travel set from Le Kasha, it's super cozy as I can’t stand the air-con on airplanes!
Why not offering him a kit with several useful things for travel? For example an eye mask, a portable charger (Kreafunk has really great designs)...
Does he already have a nice suitcase? Rimowa has wonderful and practical suitcases, really resistant so perfect for the plane
You can offer him nice stickers to put on, it will make it unique, Rimowa made a collab with Olafur Eliasson to craft beautiful stickers!