Thank you for posting your question in the Microsoft Q&A forum.
Based on your description and the screenshots provided, I understand that you want to create a SharePoint environment where specific pages and libraries are accessible only to "editors and validators," while general users cannot see the content or the navigation links pointing to them.
Based on my research, please refer the following suggestions:
-Restricting Access to Content
For your first requirement to make a page or library completely private, you can break permission inheritance and set unique permissions for that specific page or library.
You can refer to the following document for detailed steps:
-Hiding Navigation Links
For your second requirement to hide links in the navigation for users who do not have permission: Since I am not fully aware of your specific SharePoint On-Premises structure, I recommend enabling Audience Targeting for the navigation. This will allow SharePoint to automatically hide links for users who are not part of the specified group.
You can refer to the guide below:
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Note: I suggest using a Modern Site for this requirement.
I hope this information helps.
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