It seems that your relationship with him is not only that of a client but also that of a friend. You can give him mooncakes as a gift, or invite him to your home to celebrate the festival together. Nowadays, most people have only one child, and the family is also deserted during the festival. One more person means more laughter and warmth.
At that time, you can make a real-life doll for him as a souvenir. She will definitely like a humorous doll. And the most important thing is the thought. Although you two have a business relationship, he must be able to feel your concern for him. And those who have come out to make a living are wary of others. If you ignore him, he may sleep alone in a rented house all day in loneliness. I hope my answer can give you some inspiration.