[noun] + もさることながら
Fixed expression using classical verb さる (然る)
The expression もさることながら is used to acknowledge one thing as noteworthy or important, while emphasizing that something else is even more so or equally worthy of attention. It conveys the nuance of "not only X but also Y" or "X goes without saying, but Y is also remarkable." The first element (before もさることながら) is presented as an accepted fact, while the second element is highlighted as the speaker's main point.
The structure is: Noun + もさることながら
Despite the grammar point's association with ながら, this is a fixed expression built around the classical verb さる (然る), meaning "to be so / to be that way." The phrase literally means something like "that being the case as well, but…" – acknowledging the first point while pivoting to the second.