Until now the only solution would be to duplicate the dashboard, add those more advanced options to the copy and use ACL to set up access rights. Here is a recipe how to avoid duplication.
1. Create a derived metric that displays user login. Build a derived metric with Max(?[User Login]) as expression. Also set the Options to have Aggregate/Subtotals from Base both unchecked. You need to save the dossier, close and reopen it to make the metric work.

2. Create a second derived metric with IF condition that compares user login with a list of "accepted" logins. Use formula like: IF (uid In ("rprochowicz", "zjanowski"), 0, 1)

3. Add a rectangle custom shape that lays on top of the grid that you want to hide. Align position and group both of them. Apply Conditional Display logic to the rectangle

4. Make the rectangle the same color as your background to hide the underlying grid completely. Add some transparency so the grid will be visible, but inactive (for transactional grid use case)

In my scenario, when users rprochowicz or zjanowski open the dashboard they will see the grid, because the rectangle shape will be hidden. All the other users will not see the grid, because the rectangle shape will cover it completely.