I stumbled upon the WinRT XAML Toolkit for UWP. The documentation is practically non-existent and you can only see what it can do by downloading all the source from GitHub and running the sample app. The following is a video of sample app demonstrating most of the controls, as well as links to allow you to jump to specific items of interest.
The WinRT XAML Toolkit has been around since the Windows 8 days. It was ported to UWP as of Oct 2015.
The code was originally hosted on CodePlex but has since moved to GitHub: https://github.com/xyzzer/WinRTXamlToolkit
Some of the controls below can definitely be useful to you in your UWP but there are many that you should avoid using in UWP. For example: UWP now has a great date picker and I’d highly recommend you use that instead.
Note that in the video below I didn’t record every single item. Part of the reason is that the sample project had exceptions I wanted to avoid in the video.
Alternative Frame 0:02
Animating Container 0:11
Cascading Image 0:46
RingSlice / PieSice 3:31
Content Fade 5:48
TextBox Validation 7:28