I'd like to setup a Portfolio Kanban to be used at a higher level in my project and I'm not sure how it should look like. What is the key information it should contain?
Portfolio Kanban boards apply to multiple contexts. Here are 3 specific examples -
You could use it in a product development context to track high-level Portfolio Themes or Epics, under which you can have user stories on an "execution board".
In a corporate IT or business environment, you can use a Portfolio Kanban board to track "Strategic Objectives" or OKRs (Or. Key Results), which may be tied to lower level Initiatives and Epics which may be managed on a Program Board, which may further have User Stories or Features in "Execution" or "Development Team" boards.
You might use Portfolio Kanban in a classic Portfolio - Program - Project Management context where each level is tracked in separate Kanban boards to manage Portfolio "Initiatives", tied to one or more "Programs" on a Program Board, which in turn are executed using one or more Projects on a Project Board.
A Portfolio Kanban board tracking different "streams" of initiatives might look like the one below -
It may tie down, as described above, to lower level boards, such as the one below -
Portfolio Kanban can be applied to manage "upstream" work or higher level work. For example, in our own product management, we use a Portfolio Kanban board to manage our product roadmap, in terms of Themes and Epics, which result in User Stories that are developed on a separate Dev board. The Roadmap board is managed by our Product Management team while the Dev board is run by the Engineering team. The Epics and User stories are connected so we can track the completion of Themes and Epics based on the completion of the underlying user stories. The two boards and the flow of work looks like below -
You can learn more about Portfolio Kanban here as well as this excellent example on Kanban Flight Levels by Klaus Leopold, which provides a similar perspective on the use of multi-level Kanban boards without using the "portfolio" terminology.