I am trying to migrate to Pro and I am still having some issues. I am just testing things right now. I do not wish to host all of my services on ArcGIS Online (no need to use credits when you have an in house server) or in a portal. With #ArcMap, I just published to my server and then went to ArcGIS Online to create the appropriate webmaps using that data. If I am using Pro though, I need to be able to do the same thing. My biggest concern right now is updating (overwriting) an existing service so that I can make changes to the layers in an existing webmap. It doesn't appear that in Pro this is possible but I'm sure I am missing this somewhere.
To clarify, I am talking about map services. I am using Pro 2.2.