C# has been decent on Mac since the early 2010s (MonoDevelop, Unity3d), and mobile .NET has been pretty robust on iOS and Android for about a decade, with plent

C# has been decent on Mac since the early 2010s (MonoDevelop, Unity3d), and mobile .NET has been pretty robust on iOS and Android for about a decade, with plenty of NuGet libraries available. Meanwhile, Swift has a long way to go to reach at least the state of Kotlin Multiplatform, which is still mostly in beta and lacks libraries that can work outside of Android.