yes HSN is compulsory in gst migration process but you can use aadhar if your aadhar have correct name and DOB in DD/MM/YYYY format and your e-mail and mobile no. also be linked aadhar
refer this link https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://gstindiaupdates.com/wp-content/uploads/2017/01/HSN-Codes-for-GST-Enrolment.pdf&ved=0ahUKEwjVpo6JkuPSAhXHv48KHY3bDU4QFggmMAI&usg=AFQjCNEKWpnkZMluvMOqR247Qx-drrPCyw