Lil Peep's Come Over When You’re Sober, Pt. 1 sold a little more than 5,100 copies in the U.S.—that's up more than a quarter of a million percent from the frame before.

Even though Lil Peep’s songs, impromptu interviews, and social media posts feature in the documentary fairly prominently, he comes off as an enigma. Who he was remains a semi-veiled mystery, a ...