There's an object set_parent function. Why is there no get_parent?

[Pkeod]

You want to be keeping track of this information yourself as you generate objects.

Any way to get the list of children of a game object?

Well, it’s been left out by design. The rationale being that it’s all too easy to create code that traverses the scene graph, to get this or that node, in an update. This use case was very real and huge timesink at a previous games company some of us worked for. Instead, you are encouraged to setup your structure beforehand, to know what item you want to interact with using urls.