There is equal chance of this being great and being awful. Could be a tricky property to adapt for the screen, especially as a first-time filmmaker.
Assuming this will more resemble an indie and not a studio tentpole, Aubrey Plaza could do something really interesting with the part and can carry a tune. I also love the idea of Emma Stone or Jessie Buckley...Janelle Monae?
This could also take years if they don't even have the rights and funding and a script, and people who aren't currently age-appropriate (Florence Pugh, Keke Palmer, Selena Gomez) might be old enough by the time production rolls around, while people on the older cusp currently (Hathaway, Blunt, Johansson, Seyfried) might age out.