The only problem I've had with GMail via Thunderbird is that some orgs block IMAP access. I've been quite happy with Calendar as well. You don't get real-time

The only problem I've had with GMail via Thunderbird is that some orgs block IMAP access. I've been quite happy with Calendar as well. You don't get real-time sync and all of the Google Calendar goodies like viewing other people's schedules, adding Google Meet links easily, room booking and probably more are missing. But I've found that using it as mostly view-only works well, then I schedule meetings in the webUI. That being said the calendar interface has been fairly awkward in the past, so I'm really excited about this new version. I'm sure there will be some rough edges but if they can fix the alignment of events with respect to start+end time and make the view/edit dialog less awful it would be a huge win.