They already have. It was recently revealed that newly inclusion of EPAWSS in JSI upgrade program has been problematic and has become one of the reasons for major increase in cost of the whole program. Now they are reconsidering JSI program althogether because of it.EPAWSS is not for export as much as we can guess. It's a different EW suites integrated with all US systems, including F-35s.
But I agree that key allies like Japan might get the opportunity since they are already cleared for the F-35