Commenting on the fulfillment of vv. 1-2, Jeff Lindsay (https://www.jefflindsay.com/LDSFAQ/FQ_prophecies.shtml) wrote:

That prophecy has been fulfilled. Joseph could have been killed in that prison, unable to return to his friends as promised in Section 121. Instead, in April 1839, after six months of illegal imprisonment, someone in authority acted to allow the Mormon prisoners to escape during a change of venue, perhaps desiring to avoid public embarrassment by having a trial without evidence. Joseph and his brother Hyrum , about 10 days after being allowed to escape, arrived in Quincy, Illinois and found their families impoverished but alive and healthy. As was prophesied in verse 9 of Section 121, Joseph was greeted by "friends do stand by thee," and did greet him again "with warm hearts and friendly hands."

Joseph and the Church could have been destroyed by their persecutors. Joseph's few years as leader of a small and hated group could have ended in obscurity. Instead, the name of Joseph Smith is known across the world today, as was prophesied. Hell rages against the name of Joseph Smith, as enemies devise every manner of lie to slander Joseph and the Latter-day Saints, while millions seek counsel, authority, and blessings that have been given to us from Christ, revealed and restored through the Prophet Joseph Smith.

Commenting on vv. 3-9, Lindsay wrote:

That such inspiring words were written under the dismal conditions of the Liberty Jail in Missouri is a witness of the character of the Prophet Joseph Smith. In addition, the prophecy about future imprisonments and persecutions was accurate. Joseph would be killed 5 years later by conspiring enemies of the Church while he was held in another prison, Carthage Jail in Illinois. In spite of all the attacks on Joseph and all the slander, the Latter-day Saints have not been turned away from Joseph. He is loved for the honorable man that he was and for his role as a prophet of Jesus Christ. His greatest legacy as a Prophet, in my opinion, is the Book of Mormon: Another Testament of Christ, which is held in ever increasing respect by those who read it and follow its teachings. Those who read it sincerely and pray about it come to know with the heart and the mind that Joseph was a prophet of God. After being mocked for 150 years by enemies of the Church, the Book of Mormon stands stronger than ever, with many thinkers - including some non-LDS scholars - being impressed and moved not only by the text but also by the intellectual evidences of authenticity.

In fact, long before the prophecies in March of 1839 now recorded in the Doctrine and Covenants, Joseph prophesied that he and his fellow prisoners would not be killed. On the morning of November 3, 1838, after Joseph had been arrested and while he and other prisoners were on the road to Independence under the watch of guards, he told his brethren to be of good cheer, for "the word of the Lord came to me last night that ... whatever we may suffer during this captivity, not one of our lives shall be taken" (Dona Hill, Joseph Smith: The First Mormon, Doubleday and Company, Garden City, NY, 1977, p. 244). But there was little reason for such optimism at the time. In fact, his enemy, General Lucas, whose troops had taken Far West and who seemed gleeful about the Extermination Order, had just told the Saints, "As for your leaders, do not think - do not imagine for a moment - do not let it enter your minds that they will be delivered, or that you will see their faces again, for their fate is fixed - their die is cast - their doom is sealed" (Hill, p. 243, citing History of the Church, Vol. 3, pp. 202-204). But Joseph and his companions survived and returned, as prophesied.