Right now I was thinking about actually writing on the whiteboard with whiteboard markers. But we could also go for an e-ink based system, with pressure sensitivity.
Here is our little MVP roadmap:
Whiteboard can display Google Calendar events
Google Calendar can show "a whiteboard event" on a day
Google Calender can show "a whiteboard event" on a day and time block
Google Calendar can show the contents of the whiteboard event, as an attached picture (via a link?)
Google Calendar can show the contents of a whiteboard event as text
I'm beginning the thinking about the same project: https://hackaday.io/project/10874-whiteboard-with-two-way-syncronization