It's not obvious what and in which order should you do to get your add-on published.

Initially, I wrote this step-by-step guide for myself but I think it could be useful for many people.

  1. Create a project on script.google.com, develop your add-on and test it with "Test as add-on...". At this stage, any working code would be OK. An approval process is long enough to polish and test your code in parallel.
  2. Create a project in GCP console.
  3. Enable Gsuite Marketplace API in the API section of GCP.
  4. Get Project ID from GCP console (how to find)
  5. In your project on script.google.com use the menu: Resource / Cloud Platform project / Set id
  6. Publish / Deploy as add-on (select type & etc) / In Chrome Webstore developer console "Save draft". (You should have an account)
  7. GCP console / API / OAuth consent script / Specify title, Auth domains, Url, Privacy policy / Save. Permissions are tricky, for instance, if you develop an add-on for spreadsheets you don't have to not include spreadsheet access to requested permission.
  8. Upload logo 96x96 and send it for verification. Any custom logo requires branding verification so you have to wait.
  9. OAuth verification will take some time. I will write another post about it. Check this out if you have problems.
  10. GSuite Marketplace API / Configuration / Upload icons, specify Script ID from App script, and Project ID / Save changes
  11. Make promo image and screenshots and publish to testers only in CWS.
  12. Wait for OAuth to be approved.
  13. In Chrome Webstore developer console make public your add-on public. (it's better to use the old version of developer console located on https://chrome.google.com/webstore/developer/dashboard)
  14. Wait for GSuite Marketplace add-on to be published.