In my personal experience with using ArcGIS, I have only needed Pro in two situations. The first is when I'm trying to georeference a raster (I just bought one from SkyFi). The second is when I've bought a tutorial book that is based around ArcGIS Pro (e.g. Modern Policing Using ArcGIS Pro).
If you want to learn ArcGIS and not rely on Pro, you can visit the learn site and filter to just ArcGIS Online: https://learn.arcgis.com/en/gallery/#?p=agol
I won't say more, but I have personally been impressed by the rate of improvement in feature capability in ArcGIS Online. I am not aware of any plans to move Pro to macOS, I feel your pain there.