This may require a pre-1900 PoD after all but I'm wondering, perhaps in a different WW1 or a different aftermath to the war, if it would be possible to create a kind of Catholic little-Germany out of Austria, Bavaria, and most of the Sudetenland?
It seems like greater German unity was on the mind in Austria at that time and this may be palatable rather than creating a new super-Germany. I figure the most likely way to have something like this occur would be a greater partition of Germany after the war, itself I'm not sure is super possible