To some extent, a Central Powers victory is going to change the history of nationalism quite a bit; you're not going to have the whole ethos be self-determination in Eastern and Central Europe. Austria-Hungary was already a multinational state, with a significant population of Poles in Galicia who were given a fair degree of autonomy in the empire, and had a ruling class that was pretty friendly to Vienna.
Germany, of course, was a more explicitly nationalist state, and a Protestant one, so less compatible with Polish Catholicism. At the same time, though, it meant that while Berlin wanted military and diplomatic control over a Polish state, it wouldn't necessarily require any kind of integration into the empire, and a Polish Kingdom could be autonomous domestically. Ultimately, that would very likely mean a German monarch, but that's not necessarily a dealbreaker domestically; plenty of non-German states had German monarchs.