WinCE 6 Platform Builder was based on Visual Studio 2005 I think.

Building applications for WinCE 6 was also only supported with Visual Studio 2005 or 2008, which put a hard cap on available language features and development OS support. I had the thankless job of trying to port C++ code from Linux to WinCE 6 in 2014, and even then VS2008 felt way behind.