I'm having the same objective : release a simple game, with adds to make (or not...) money via the app Store.
My researches brings me to Google Ads, and Google provide a Python version of their Ads API.
I hadn't gone more further in that (I'm not at this point of the project), but here is the Google solution :
I'm not sure it will be easy to use with Pythonista, or simply possible, but it looks promising and probably easiest than Object-C for Python programmers.
As I was talking about it in the "Next Pythonista Most wanted features" thread, I really think that being able to support such a feature in Pythonista should bring a lot of people to develop with.