Old soldiers like them are usually straightforward. What gift to give to your father should be based on your father's personality and preferences. It is recommended not to be too luxurious or grand. It is better to give a special, creative, and simple gift.
Real Q-version doll: Old soldiers generally like to wear military uniforms. You can make a real doll based on the real photo of your father in military uniform. You can create the costume according to your own imagination. However, it is best to have a heroic and serious posture. Hehe. Your father will definitely like it.
Green potted flowers: Middle-aged and elderly people like to play with flowers and plants. Give your father some green flowers that are good-looking and beneficial to health. I believe your father will like it.