At Union Hall, “New Stuff” frames rock and pop as a living, local practice rather than a finished product. Phoebe Robinson leads a bill that also includes Jordan, Carlos, Usama, and Siddiquee, each bringing distinct rhythms and stage habits to the same room. The setting matters in New York, where small venues have long served as first drafts for songs and scenes before they harden into industry narrative. The most telling moments tend to come in the seams between acts, when the night’s shared language becomes audible.