I was playing around with this GDrive client for commad line and I packed some scripts into a work-in-progress addon. The client is very basic, has no sync function and it is a little messy to config it the first time because you need to access via ssh in order to copy/paste the authentication key for your google account.
After that, my script just download/upload content of/from a specific folder, and can be launched at kodi's startup.
By now I just added an option to get all .torrent files from that folder and move them to transmission watch folder. Another uses I am thinking about are a "sync" feature for emulation save files, auto-download gdrive backed up pictures from your phone...
If anyone has a proposal or just wants to try/play with it, here is the source code and the addon zip: GitHub - bite-your-idols/script.pigdrive: Google Drive as a kodi addon for Raspberry Pi.
enjoy!