I was partially wrong, it wasn't for the PSP, rather something else,

https://apple.slashdot.org/story/10/11/25/0432204/Sony-Adopt...

https://www.slashgear.com/sony-snap-connected-device-app-fra...

And for completness here are some articles about the C# SDK,

https://venturebeat.com/games/ps-vita-sdk/

https://www.codeproject.com/Articles/535325/Hello-World-on-t...