Thanks for the reply, I tried that too using PublisherRetail as the https://learn.microsoft.com/en-us/microsoft-365/troubleshoot/installation/product-ids-supported-office-deployment-click-to-run. It did perform the install, but I noticed that it added "Publisher 2016" as a separate entry in add/remove and it didn't appear to be part of the O365 suite as compared to a fresh install which includes Publisher. Meaning, if I do a fresh install of O365 without excluding Publisher then it's bundled with O365 and is not listed as a separate entry in Add/Remove. I'm not sure the ramifications of this being installed as a separate product but I was worried it wasn't correct. It seems there is a difference between ProductID and ExcludeApp, since one is mentioned as a Product and one is an App? Perhaps if there was an "IncludeApp" keyword in the XML that would work better.
At any rate, after all that - my subsequent tests seemed to work OK using the original XML that I mentioned in my first post. Not sure if something went wrong with Intune during my first test but I tried 2 more times using the XML which "de-excludes" Publisher and that seems to do the trick now. WHEW! 🙂