The New Whiteboard is available NOW in Teams, web browser and Android app.
Updated versions for the Windows app and for iOS devices are expected in late October.
You can find out about all the new features on this technical community post from Microsoft …
Welcome to the new Whiteboard! – Microsoft Tech Community
New or updated features include the new Sticky Notes and Grids, New templates for Whiteboards, Reactions, and easier “snap to” functions.