I am not sure where you are seeing conflicting answers. The answer is no you can not make changes to portal code without making your portal in supportable by ESRI. If you want those new widgets you will have to wait for the next portal version.
Robert, thanks for the reply. I'm trying to understand why I can't add widgets in, as long as I don't change core portal code. This is extremely limiting and kind of flys in the face of innovation for portal.
It is quite simple the portal product has been tested and certified with the widgets it comes with and adding widgets that did not come with that version means there is possibility for errors that the ESRI tech support team are not prepared to handle and this will mean your portal will no longer be supportable.
Right, understood, but it seems that it should be that they support everything up until the widget that you installed, but not past that. Ironically, I'm wanting to use the nearby widget (Esri developed) but it is not in the current 10.4.1 implementation of portal.
But if you made the change to portal (albeit an ESRI widget) what is to say you did not tinker with other code. So simple rule is if you modify portal in any way it is no longer supported.
FYI, with the release of ArcGIS Enterprise 10.5.1, Web AppBuilder embedded in Portal for ArcGIS now supports custom widgets. Please see this blog,
Hope this helps,