These are working groups that have formed to collaborate on specific Open edX topics, covering product, engineering, marketing, and collaboration.
See our public Open edX Working Group calendar which contains the schedule of our recurring Working Group meetings. On that calendar, when you open it, you’ll see a button that looks like this:
Push that button (on the calendar, not here!) to add the shared calendar to your Google Calendar account. We also have the calendar ID to open in specific app in case that helps.