Note that that's not a Raman spectrometer, just a conventional grating or prism-based instrument. 3 nm resolution isn't too bad, though. Could be good for evaluating aquarium/houseplant lighting and things like that.
A Raman spectrometer is still a fairly exotic piece of hardware, requiring a laser, a notch filter for the laser's wavelength, and a very good conventional spectrophotometer to look for low-level sidebands. There have been some homebrew Raman implementations -- e.g., Ben Krasnow's at https://www.youtube.com/watch?v=tRrOdKW06sk -- but nothing that would fit on the back of a smartphone.
A Raman spectrometer is still a fairly exotic piece of hardware, requiring a laser, a notch filter for the laser's wavelength, and a very good conventional spectrophotometer to look for low-level sidebands. There have been some homebrew Raman implementations -- e.g., Ben Krasnow's at https://www.youtube.com/watch?v=tRrOdKW06sk -- but nothing that would fit on the back of a smartphone.