Top Level as Default Page - Selective Access List
I have a Selective Access List which has an internal hierarchy within the list (Parent items that are not from another List) published as Page Selector to a Dashboard. This example is a List of Budget Owners with a top level for 1 section of Budget Owners
So for a User with Access to the Tobi Group the Dashboard will open up on Wayne, not on Tobi Group parent item
By default, Anaplan will show the first member of the lowest level of any list or hierarchy, in this case that is Wayne, so that makes sense why it showing that way.
There is a newer option to use the top level as a default, but that would start you at the "All Budget Owners" Level if you have access to the whole list, and if you don't have access to the whole list then it will follow the default of the first list member of the lowest level.
Then the final way you can control the default first item is to select that as a default in the dashboard itself, but that will also not honor selective access if you don't have access to that particular member.
The only other option that comes to mind, and this is certainly a little out of the box thinking, and it might not meet the process at all, but if you can trick/force the user into clicking Tobi on a different dashboard first, then this would sync across dashboards and display as exected here once they navigate to this dashboard. The only time that I have actually gotten this to work is when using the "open different dashboard depending on dashboard" Action, so if that somehow fits into your process then this might get the job done!
Unfortunately, this one will likely be very tough and probably unachievable.
That is a little bit disappointing as it is difficult to explain to non Anaplan people that the Dashboard needs to open up at the lowest level (if Selective Access is enabled & they don't have access to the top level) - definitely lowers the User Experience