This question needs to be analyzed on a case-by-case basis. However, judging from your description, your boss should be a good one. You should give this gift as a friend, not as a subordinate. I think it will feel best this way.
It is not difficult to give anything. Isn't it popular to take a group photo of a family of three when a child is just born? So you can ask them for a group photo of them, and then customize a family doll online. The price is very suitable for your white-collar status, and it will not cause any misunderstanding to your boss. Therefore, I recommend giving a real doll. And the doll is permanently preserved and has great commemorative significance.
Of course, there are many other gifts you can give. You can go to Taobao, Tmall, Baidu Youa, Paipai.com and the like to have a look. There are many kinds of gifts, and you can choose freely. By the way, you can also buy something for the baby, which is more practical. Like milk powder, diapers, etc. . .