How can I see the sharing settings of a board I don't own?

@Graeme Harker - In short, no.

I don’t believe there is currently any role in any plan that allows for non-board owners to see/modify a board’s Share settings if the board owner has not given them access to the board, e.g., the “Anyone at [TEAM NAME] team” is set to “No access”. This is described in the Roles in Miro Help Center article under Company level → Company Admin:

There is at least one existing Wish List post in which other Miro users are asking for better/more admin controls.

I would suggest that you add your comments/upvote this idea → Better Admin Controls.

And if you don’t feel this--or any other ideas you may find in a search of the forum--clearly capture what you are trying to accomplish, you can always create your own Idea in the Wish List category by following the guidelines here: Wish List: Everything You Need to Know.

If you do create a Wish List Idea post, I would also recommend that you post a link to it back here, so that future readers of this post can quickly get to and vote for your Idea.

Lastly, don't forget to vote for your own Idea.

As a “Company Admin” in the team’s “team” settings I can remove access to all boards in the team from outside of the team on a blanket basis but that’s a “sledgehammer” solution.

If you are referring to this setting:

Allow me to clarify this setting. When you however over the “i” for more information, you’ll see:

This is referring to adding/inviting people at the board level, which done here in a board’s Share settings:

Therefor the “Allow non-team collaborators” settings will not any team member who has board access from enabling public access to a board.

Outside of the Enterprise Plan’s Sharing Policy feature, there is no way to stop any team member with access to a board from enabling public access to the board via the “Anyone with the link” feature (see the Collaboration with Guest Editors Help Center article for more info on this feature).