I think it's still a matter of trying to contact a programmer who wrote such a program and ask if
(s
)he will share the code. Finding still-functioning links to Windows CE-based programs, open source or otherwise, is pretty hard these days. The above link appeared to take me to Trevor Hart's site yesterday, but strangely it redirects to an unrelated page today.
(His pages are still available on the Wayback Machine, and the download links still seem to be working from the archived pages.
) There used to be a lot of folks on xda-developers.com sharing a lot of stuff, but of course again the Windows Mobile
(CE
) stuff is all old now. I found a similar program written in .NET on this page:
https://forum.xda-developers.com/showthread.php?t=513858
Maybe you'd get lucky trying to contact that developer.
Codeplex used to be a place for what you're looking for:
http://www.codeplex.com/
. . . but it's pretty much shutting down as of next Monday. I searched it for a GPS speedometer project, but nothing came up.