Nelson played in all 27 of NDSU's games, with five starts as a freshman and was named the Summit League Sixth Man of the Year after averaging 6.3 points and 3.7 rebounds per game.[6] He became a starter as a sophomore and averaged 11.6 points and 4.9 rebounds per game.[7][8] During Nelson's junior season, a highlight reel of his play went viral in early January 2023.[9] As a junior, Grant averaged 17.9 points and 9.3 rebounds per game, as well as shooting 52.1% from the field.[10] These stats also earned him his first All-Summit First Team and All-Summit Defensive Team honors.[11]
Following the 2022–23 season, Nelson explored his options in the 2023 NBA draft but ultimately withdrew to return to college for his senior season. On June 12, 2023, he transferred to Alabama after spending three seasons at North Dakota State.[12] Nelson averaged 11.9 points and 5.9 rebounds per game. He announced he was returning for his final season at Alabama.[13]