Think of how disoriented and isolated Nephi must have felt. With respect to the people living in the world that Lehi and his family left, Nephi and his people were out in the middle of absolutely nowhere. As far as they knew, they were living on an island of the sea and Nephi, of course, knew that Isaiah recorded the promise that God would not forget even the people on the isles of the sea. At this point in time, Nephi and his people had likely not yet had an opportunity to explore far enough to really know how large of a land they were inhabiting.
Nephi had built a temple. He was trying to reestablish things and bring order to his people. He must have also wondered if this work would be for naught, because he also knew that there would be great wars and that his people, the Nephites, would eventually be wiped out. This must have been a most depressing vision. Nephi was undoubtedly struggling with concerns of anonymity, of annihilation, and extinction. So, when Nephi was brought to the understanding of the voice of his people speaking from the dust, it must have brought great hope.
In 2 Nephi 26:16, Nephi had first prophesied that the writings on the plates would speak from the dust, alluding to Isaiah 29. Nephi then spent a great deal of time discussing the role the plates of his people would have in gathering Israel. The whole of chapter 27 then discusses how this prophecy about his words speaking out of the dust would be fulfilled. Nephi quoted from a section in Isaiah 29 and explained how God would bring about the great and marvelous work that would come forth—the marvelous work and a wonder. Isaiah prophesied that God would not forget the people whom Isaiah was addressing. Neither would God forget Nephi and his people. Nephi understood that his posterity would have an important role to play in the history of Israel and that the record made by Nephi and his people would change the hearts of the whole house of Israel. God would keep his promises and somehow this prophecy would be fulfilled, if Nephi would only keep the records and do what he was commanded to do with the plates.
Book of Mormon Central, "How Are the Words of the Book of Mormon Like ‘One That Hath a Familiar Spirit’? (2 Nephi 16:16)," KnoWhy 491 (December 16, 2018).