Are many Protestants saved?
By the mercy of God a certain number of Protestants are saved, but their Purgatory is for many long and rigorous. It is true they have not abused grace like many Catholics, but neither have they had the marvelous graces of the sacraments and the other helps of the true religion, thus their expiation in Purgatory is prolonged.
https://www.catholicculture.org/culture/library/view.cfm?id=6253
Yes, they can be saved, but not as Protestants. Before their death, they would have had to become Catholic, at least in their final moments. Every one in Heaven adores the Holy Trinity and the Holy Eucharist, venerates or worships the Blessed Mother with hyperdulia as Queen of Heaven and the Immaculate Conception, and Mediatrix of All Graces, and everyone even in Purgatory had to first believe in Purgatory to go to Purgatory. No one goes to Heaven without accepting the full Truth of the Catholic Faith taught by the Lord. The Saints in Heaven, and even the Holy Souls in Purgatory, whose intercession we seek, have a better understanding of the Faith than we do. They know all the Truths of the Faith are 100% True, including Purgatory, Heaven, the Intercession of Saints and of Angels etc.