The assumption I would drop is “a workspace always corresponds to a self-contained process”, because a Workspace is a modeling-time container only. It is the folder structure that the SME, the Preview Application and the Workspace Converter expect (A12 Modeling Workspace). At runtime there is no workspace boundary. The deployed application loads the models located under import/models, and an existing Workspace can be imported into a project (Importing a Workspace). Therefore, one Workspace per process owner and one overview across all processes is not a contradiction.
For the map itself, on top of what Patrick already described: the clickable entries are Interactive Tiles in a Content Model, whereby each tile’s click event navigates into the module of the respective process (Content Modeling → Interactive Tile). Modules, regions and layout come from the Application Model (Application Modeling). Which clusters a user sees is not part of the map but role-based (Authorization).
Whether the map is a Content Model or a Dashboard region depends on what a single tile has to show. A Content Model is presentation content: free layout, text, images, tiles that navigate. The Dashboard layout arranges views as tiles, so it is the option if a tile itself has to render live data through an engine, for example the open holiday requests of that process, at the price of one view and its models per tile (Dashboard). Both can be combined, with the Content Model as the map and one module per cluster below it.
Two caveats when you merge the Workspaces into one application:
Important: model ids are global per application, not per Workspace. If the HR holiday Workspace and the business trip Workspace both contain a Document Model with the id Applicant, one of them wins after the merge and the other process silently references the wrong model. Therefore, I would recommend a per-process id prefix (hr_holiday_Applicant, hr_trip_Applicant) before the second Workspace exists, because renaming ids later means touching every Form, Overview, Relationship and App Model that references them.
Note: the map is content, not a generated view of the processes. A12 provides no “process map” mechanism by default, so nothing derives the tiles from the existing processes. A new process appears in the map if and only if someone adds a tile to the Content Model. A removed process keeps its tile until someone deletes it. If the map has to be maintained by the process owners themselves, this is the part that will drift.
The alternative is one deployed application per process plus a plain link page in front of them. It costs a deployment, user and role setup per process, and a cross-process overview list becomes impossible, but the process owners stay fully independent. From my point of view this is only worth it if the processes have to be released independently.
Small reminder because your topic is tagged 2025.06: the links above point to 2026.06, because that is where I checked the wording.