Unique Page Per Registered User

All page slugs are unique, you cannot have duplicates even if you tried. You can create pages with any unique slug you like. They can match a user’s name if you like. So you can create these pages manually without any plugin or special code.

If you want this to happen automatically, it’s a different story. The best solution depends on where the page’s content is coming from. WP already has similar functionality for authors. What’s actually shown depends on your theme, but it’s typically a bio and a list of their posts. This only works for users who have published posts though, not all users.

If you want similar functionality for all users, you could set up something similar. The URL should have a constant permalink element, for example example.com/user/foo/. The /user/ element can cause a particular template be used which finds data for user “foo” and displays it.