So, I've searched the internet and i feel kinda lost since the amount of books that cover this Topic seems to be very small. That's why I'm reaching out to you in hope of getting some advice here.
If you were going to buy a single book, I would recommend "The Teutonic Knights: A military history" by William Urban; who is the academic grandmaster of Teutonic Order history.
Now that book focuses on the Order; it's creation, adventures and of course its core involvement in Prussia and the creation of the Teutonic State and its political struggles with Poland over Prussia.
If you want a wider view of the northern crusades; Erik Christiansen's "Northern Crusades" covers Prussia, the Wendish crusades, the Swedish crusades and stuff like that.
I'd also like to add Aleksander Pluskowski, The Archaeology of the Prussian Crusade: Holy War and Colonisation, London: Routledge, 2012 to your book list.
If you can by chance understand German, the works by Jürgen Sarnowsky should also be your starting point of reading the relevant topics, like Die geistlichen Ritterorden: Anfänge - Strukturen - Wirkungen, Stuttgart: Kohlhammer, 2018 and Der Deutsche Orden, 2. Aufl. München: C. H. Beck, 2012.