Mediocre New York Times article about what some non-binary "professionals" (and some cis "professionals" think non-binary "professionals") should wear for work: https://archive.ph/fZT06
Even better piece written by one of the interviewees, a non-binary anarchist lawyer: https://medium.com/@AndyEyeballs/non-binary-fashion-tips-for-professionals-872f38a25c43