Very familiar with add-ons for Kodi, working with json API's and Python. I've worked for the past 6 years creating quality add-ons for myself and others. My last Job was creating a private add-on which talks to a PHP based server to retrieve video playlists. For evidence of my work, please contact me.
Depending on the details of this job, we may be able to have it completed in a day or so. I prefer to give you a worst case for estimated time to completion.