Is is possible to share any dashboard component across Workspaces?

Parameters can be shared between Maintenance units and even Workspaces, but components can’t. That’s the reason you can see the parameter when the workspace is flagged as shareable. If you like to use a button in another Maintenance Unit or workspaces, you need to put it in a surrounding dashboard. You can place dashboards in other dashboards by using the embedded component (yes, this is the reason for them to exist). With this, you can embed every component everywhere. I hope this helps.