This is very confusing to me. The word "Prussian" means a lot of different things and has a lot of connotations (such as imperialism, militarism, ...), while simultaneously describing a geographical region that was part of Germany before 1945, and also a political state which has almost nothing to do with the region...
Since Prussia started out as a very small state and conquered pretty much all northern Germany with a combination of force and political malice, and then united Germany within their uncontested leadership, it is hard to have any idea who really identified themselves as "Prussian".
I have a fictional book (made for German language learners) that takes place in inter-war Bavaria, there is someplace a joke about people arriving late, and their professor answer them:
Pünklichkeit ist eine Preussische Tradition
(German for : Arrival on time is a Prussian tradition)
This particular quote really made me scratch my head because this book was only about Bavaria, which on paper has nothing to do with Prussa, so why would the guy give a damn about so-called "Prussian tradition" ?
So who used to consider themselves "Prussian"? Did people that were in political Prussia, but not geographical Prussia, ever feel "Prussian", or did they always continue to consider themselves Rheinlanders, Hessians, Hanoverians, etc, etc... ?
In the case where someone was part of Prussia, but did not feel "Prussian", is there a case where they claimed they were illegally occupied by Prussia ?
Last but not least: Is there still people who consider themselves "Prussian" today (especially refugees from annexed eastern Germany and their descendants ?)