@VMC - No, they are not. Miro does not publish any board links on the Internet. Only members of the Free Plan team in which the boards are located will be able to view them.

You can read more about this in the Public Boards vs. Private Boards Help Center article:

The only way the board could viewed publicly/those outside of your Free Plan team is if you set the following and shared the link:

Thank you so much Robert!!!!!