My ultimate goal is to create a URL that is unique and cannot be guessed/predicted. The purpose of this URL is to allow users to perform operations like verifying their email ad
A Guid is not meant to be a security feature. The standards for creating a Guid make no claims about how secure it is, or how easy/hard it is to guess. It simply makes a claim about it's uniqueness.
If you attempt to secure your system by using a Guid then you will not have a secure system.