NCT is a very popular K-pop group with many members and sub-units. They have collaborated with other artists, but their first big collaboration as a group was not specifically with another K-pop group. However, they have worked with many artists within their own company, SM Entertainment, through projects like SM Station, which involves collaborations with other SM artists.
NCT’s sub-units, like NCT 127 and NCT Dream, have also participated in collaborations with other artists, but these are not typically with other K-pop groups outside of SM Entertainment. For example, NCT 127 has been involved in projects with international artists, but these are not specifically collaborations with other K-pop groups.
NCT has released many successful albums, including Empathy, Resonance, Universe, and Golden Age. These albums have been very successful, with Resonance selling over 2.6 million copies and Universe becoming their most pre-ordered album with over 1.7 million copies.
Overall, while NCT has not had a major collaboration with another K-pop group outside of SM Entertainment, they have been very successful in their own right and have contributed significantly to the K-pop scene.