"Exported from a dream" ideas are 50-50 between "cool but unpolished" and "total fucking nonsense."

Personal favorite might be a black market for transdimensional metal albums. Ephemera, lost works, what-ifs, etc. Overwhelmingly metal because that's the only genre where people obsess over the details but can also keep cool about it. If what came through was k-pop then it'd stay secret for a matter of nanoseconds.