Thunderbird and Google CalDAV
Ugh, once again some fiddling was required to get a new Google calendar in Thunderbird. Things have changed in recent versions of Thunderbird, and while some calenders carried over, the method I documented for adding them, turned out to be not working anymore. This involved adding CalDAV URLs starting with https://apidata.googleusercontent.com/caldav/v2, but it seems like I needed to step back down to v1 or a versionless version of Googles CalDAV server. Anyway, here’s the procedure:
Under Google account setting, create an app-password with access to your calendars. Then in TB, add a calendar with your Google username and a location like https://www.google.com/calendar/dav/_____/events/, where ____ is your email address, or the group address of the calendar you wish to add (to get this, on the Google Calendar website, check the calendar settings for the one you wish to add). Use the app-pw in the pw-prompt and presto.