As far as intervention in specific cases goes, the Pope succeeded in replacing 500 Jews who were imprisoned in Rhodes to an improvised refugee camp in southern Italy. After Mussolini’s downfall and the German conquest of Italy, the Nazis rounded up 12,000 Jews in Rome for deportation to concentration camps. In reply, the Pope sent a message to Himmler threatening to publicly denounce the deportation unless it was stopped, which it was. When the Roman Jewish community was threatened with deportation unless they met a Nazi demand for gold, Pius offered to make up the difference if the Jews were short. He ordered the Italian Bishops to hide Jews monasteries and convents, and his many in his summer residence, the Castel Gandalfo. As far as the Jewish opinion of Pius XII goes, the chief rabbi of Rome, Israel Zolli, said that “no hero in all history was more heroic than Pope Pius and his readiness to defend the children of God,” became a Catholic, and took the Pope’s own birth name, Eugenio, at baptism. The Jewish historian Pinchas Lapide estimated that the Church under Pius XII rescued 860,000 Jews from the Nazis, which is about 37% of those who survived the war. Altogether, that certainly does not describe a coward Pope. I took almost all of that from The Real Story of Catholic History by Steve Weidenkopf, which provides plenty of citations, so if you need sources, I can provide them.