.Net Core on Windows has support for loading assemblies that reference COM interfaces and the win32 API, along with other things that aren’t supported elsewhere

.Net Core on Windows has support for loading assemblies that reference COM interfaces and the win32 API, along with other things that aren’t supported elsewhere like C++/CLI. That’s why loading System.Windows.Forms still works, it’s not part of .Net 5+, but it can still load the assemblies on Windows (they still use GDI, etc under the hood).