Details page with parameter in the URL


I'm relatively new to Shiny, so maybe I'm just overlooking something very obvious here.

I'm looking for a clean way to build a page of my shinydashboard to only show a single item in my database. I need to be able to link to it (at least from other pages inside of shiny).

The idea is to have a page like /item-details?itemId=1234 or /item-details/1234 and showing only the item with that id, there might additional contextual data show, but all should be based on that item. I cannot find a good example on how to achieve this, without adding some kind of input in the UI to select the itemId.