Unfortunately there is very little published English language books on Pius XII that deal with the subject. Most of what is discussed is limited to Vatican conduct in the immediate postwar period, especially regarding pontifical involvement in various people's escaping Europe via charity organizations funded by the Vatican. For primary documents you can browse the "Acts and Documents of the Holy See Relative to the Second World War" online. For the rest of Pius XII's documents we have been waiting for those to open for decades--and they did open recently in 2019. Due to the pandemic access to the archives has been sporadic and short-lived. A new wave of books and articles on Pius XII will be written and debated, but for now all we have is conjecture.

I wish I could give a better answer, as this area of study is important but has not been adequately covered in the many English language secondary sources--and I have no skill in the other relevant languages so I cannot comment on the status of that historiography.