PocketPC was based on the Windows CE kernel which was written pretty much from the ground up. It planted its roots prior to both 9x and NT kernels with pieces as far back as the early 1990's
There is cross pollenation of programming techniques and features as all codebases evolved, e.g. in globalization, thread scheduling, memory management, device abstraction, and user input. Not that isn't expected in a company that has spent the last 25 years writing OS pieces.
Why would you doubt they'd do that?