Looking at these docs, it looks like Xamarin Forms sorely needs better font support.
There are two main issues:
- Needing to use a custom renderer on Android means that we need to create a plethora of custom controls. Especially for composite controls where we want to change the font of an internal label, it's painful.
- The font names themselves are different on the different platforms. The WP version is frankly crazy. I know there are differences "under-the-hood," but those differences are exactly what a framework like Xam Forms should be hiding. The framework can specify that the fonts need to go into a specific folder; add blah to a plist, etc. But then it should figure out what the names need to be per-platform.
Fonts that are licensed for mobile use aren't' that hard to find; Google Fonts is one large library where most of the fonts are under Apache 2 or SIL.