Should a navigation be specific to a page?

Let's say a mobile application has 2 interfaces: one that lists items, and the other that displays the details of one of these items. Both of these interfaces have the same navigation bar on top of the screen.

Should the 2 interfaces be 2 pages, or 2 tabs?

2 pages mean that when I click on an item from the list, a new page opens on top of the current one. 2 tabs mean that there is 1 page, and when I click on an item, the content of the page changes, except for the navigation, that stays there.

It feels weird to me that 2 pages would have the same navigation bar. If the navigation bar is the same, it probably means that these pages should not be pages, but tabs in a single page.

I checked on Facebook, Twitch and Slack, and I never saw a page having the same navigation bar as its parent.

So, if both interfaces have the same navigation, should these interfaces necessarily be tabs and not pages, or is it fine that they are pages?