What to choose: 1 Xamarin & UWP or 2 Backend?

Question

ASP.NET

Good afternoon!
I have a lot of experience in Backend, also made desktop applications in Xaml (WPF, some UWP).
I'm changing jobs.
There is 1) a backend offer (C#, ASP.NET) and 2) a Xamarin + UWP offer.
It would be interesting to delve into Xamarin + UWP, but I doubt it ..
What do you think is more promising in terms of new experience and its demand in the future?

Answer 1

It is more promising to extract oil.
Choose what interests you. Technologies change too quickly and often to be sure what will be in demand in the future.

Answer 2

in terms of 10 years the same, in terms of 20 years both will die or be replaced