I have a cross platform portable app that on Android includes printing. I've been working on UWP printing. The problem is there is no way unless I'm missing something to bring up the UWP PrintHelper because it uses a Windows.UI.Xaml.Controls Page not a Xamarin.Forms Page. Unless I'm missing something seems to me there needs to be a solution that is as easy as printing was for Android and I hear is also easy on iOS (I don't own a Mac yet so can't confirm).
I found a partial solution here which can be called as a class and implements a Webview which is not displayed. I cleaned it up a bit and added the "completed" callback that is raised when printing is completed. Problem is I don't know of anyway to get rid of that Webview once it's done so that causes a memory leak.