You can share a board with anybody, including people who are not registered with Miro, by making the board accessible via a public link for visitors.
Open the Share window and choose the level of access for Anyone with the link. You can choose between view, comment, and edit access (based on your subscription plan and settings).
Copy the board link and share it with whoever you want to give access to. People who follow your link won’t need to register with Miro to access the board. Registered users will appear on the board under their own names, while unregistered users will be shown as visitors.