I tried sample on vs for Mac:
It compiled as is, but the packages were old. I tried updating everything (Xamarin forms and FFImageLoading). All worked including SkiaSharp in android and iOS, but the forms version didn't. Error is below.
Could not install package 'SkiaSharp 1.60.1'. You are trying to install this package into a project that targets '.NETPortable,Version=v4.5,Profile=Profile259', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.