Digging out this old topic. I successfully could sync my private calendar with vdirsyncer to my Mirror. What I would like to add are the birthdays of my contacts. The issue with this one is, that they are not an acutal calendar.
I tried with another device specific password to bypass the two-factor authentification which I was assuming is the issue here but no success.
I would even be fine in manually downloading an .ics with the Birthdays but have no idea how to extract them from the contacts. Does anyone have been successful?