xamarin.forms has support for uwp/wpf (windows), linux (GTK#) and mac (https://docs.microsoft.com/de-de/xamarin/xamarin-forms/platf...) it's not highlighted that much and for some stuff you need to create native views. but it works smoothly and you can do a lot of stuff. for some stuff you still need to configure native views, or call into native apis, but still it's pretty nice working and looks better and is faster than most electron stuff.