Review for Provider for Google Calendar by Adam Reece
Rated 5 out of 5 stars
Has been working splendidly until the recent rate_limit_exceeded issue.
To everyone else leaving a review due to this, please remember reviews are not the place to request support.
I've opened a thread on the official support medium at Github here if you'd like to leave a comment, or just an upvote to show indication of increased severity:
https://github.com/kewisch/gdata-provider/discussions/296
Thanks for the add-on though. Recent Google API rate limit aside, this add-on really does do what it says on the tin very well.
To create your own collections, you must have a Mozilla Add-ons account.