Hi Anas,
the solution actually was to raise a message at SAP Support ;-) Normally in up-to-date Fiori applications there should be an exit hook to disable the navigation button. So for our scenario the applications didn't have this exit hook implemented but SAP was able to deliver an update with a note.
BUT: for one application I figured out that this exit hook is even available even when it is not explicitly implemented in the app. So what we did was to implement the function getHeaderFooterOptions() in the custom view. Our need was to disable the NavBack button only when the application runs in standalone-mode for e.g.:
getHeaderFooterOptions: function() { var objHdrFtr = { sI18NMasterTitle: "NAME_OF_TITLE", onBack: true }; var m = new sap.ui.core.routing.HashChanger(); var sUrl = m.getHash(); if (sUrl.indexOf("Shell-runStandaloneApp") >= 0){ objHdrFtr.onBack = false; } return objHdrFtr;
}