How to allow anonymous users to view page? I would like to make a new page, before publishing it I'd like to send it to other people to review/approve the content without having to log in.

Is this possible?
I think it is hard to achieve. 
However, using Access Unpublished module, maximum you can do is you can provide the specific URL to anonymous user(which includes all), so they can see the unpublished node with that specific URL(So, this way you are hide content from all other users, as they have not that URL), however they can not edit. For Editing option you have to set the separate user role, hence it ends up with login.