C# is still the flagship language of Microsoft. As stated in the DotNetCurry magazine (issue 40; Jan-Feb 2019), Xamarin is still alive and well in 2019 and developer support is still strong
Taking this into account, Xamarin is still useful for building Android and iOS apps in 2019
Since there are already 2 best answers, a third shouldn't bother anyone. Bring it in!
Just kidding. Check if making this answer as the best answer removes the best answer tag from the others.
P.S. Don't worry, I have a screenshot handy as a proof.