KBA 2841820 explains that it is impossible to restrict the use of any Project Systems (PS) in Fiori Application.
For instance, we cannot restrict the use of App. "Project Control" to the company code of the user...
It is "quite" surprising because those App might give access to very confidential data, and apparently it is not considered as a bug.
Did you meet that issue ? And do you have a workaround ?
Thanks for your contributions.