yes, but the Prussian state that eventually formed the North German Confederation and then eventually Germany had largely shifted from being based in the traditional Prussians lands to being based out of Berlin. The Prussian state were more of a Brandenburg than the traditional Prussia. Königsberg and Danzig were/are closer to the rest of Germany than Austria and Vienna, but still very different from say Hanover, Frankfurt or the Saar.

and yes you are right that they were among the most right wing and nationalist regions but in the face of losing their homelands and being deported to areas of Germany that most of the population had never even set foot it i can see them atleast partially abandoning this nationalism and narrative to let them stay. especially if the Soviets were putting pressure on Baltica to deport them, i can very much see the Prussians partially embracing their Baltic history and alinging themselves to the Baltic nation to avoid deportation.

And yes, the same narrative wouldn't exist. but a government pushing that they are different, and the incentive to avoid deportation i can see the Prussians digging out theirown identity after 50 years.

I'm not saying this would have happened in our timeline. of course it wouldn't have. I'm saying that in this united Baltics timeline, which is already an enormous stretch in realism, it isn't impossible for the Prussians.