Why is Prussia a democracy?

Hello all,
I'm just curious why Prussia, in particular, is mentioned to be canonically a democracy-- the only human nation to be so? Historically, Prussia was the domain of the Teutonic Knights on the frontiers of Christendom; whose hard-fighting, militant culture and ideals influenced it as it evolved into a duchy, then a kingdom, then the German Empire.
The Hohenzollern monarchy was also central to Prussia's military culture-- from Frederick the Great, the personification of "Enlightened Absolutism," and his wars over whether he was the "King in Prussia" vs the "King of Prussia"; to Otto von Bismarck's work to create a German Imperial dynasty that could outshine the Habsburgs; to the humiliation of the Bonapartes at the Palace of Versailles; to their own humiliation at Versailles again.
I understand that history evolved very differently in this timeline, and a non-monarchical faction might be needed for diversity. But rather than Prussia-- a Crusader frontier-state which became a strongly-conservative, militant monarchy (rather like New Antioch), why not the Italian states? Venice, Florence, Genoa, and Pisa were also deeply Catholic, but had a strong tradition of urban republicanism. Alternatively- there's Novgorod, Poland, the Swiss Confederation, or the Hansa. Perhaps, with the destruction of Byzantium, the Greeks have returned to their democratic roots, claiming the legacy of both Athenian Democracy and the Roman Republic in the absence of the Basileus.
And among Muslims- various nomadic/tribal systems (Bedouin, Berber, Caucasian, Hausa, Touareg, Somali, Afghan, Turkic, etc) all had varying degrees of democratic participation.