Programs for Windows CE that include SH4 versions are a bit harder to find, since there were only a few CE devices produced that used that processor. However, one cool thing is that Adobe released a Windows CE 2.11 version of Acrobat Reader 4.0 that was only compatible with the SH4 processor. Have a look in the Software Compatibility List here:
https://www.hpcfactor.com/scl/
There is a small number of SH3 programs that will work on an SH4 device, but they are limited almost entirely to programs written for CE 1.0. I talked about this here:
https://www.hpcfactor.com/forums/forums/thread-view.asp?tid=13677
Also, there are runtime libraries within which you can run programs that are not processor-specific. Such runtimes include Orbworks' PocketC, Microsoft eMbedded Visual Basic, and .NET Compact Framework 1.0.
(PocketC programs have the file extension .app, while eVB programs have the extension .vb.
) The runtime libraries themselves are processor-specific, but each of these has versions for the SH4 processor. .NET CF 1.0 for Windows CE 2.11, and PocketC, can be found in the SCL above, while the eVB library files are here:
https://www.hpcfactor.com/developer/
Look under the heading "Handheld PC Global MFC / VBRT Redistributable."
I agree about the existing YouTube videos about CE history. They're full of errors: wrong desktops, etc.
What touchscreen CE 6 device do you have? There weren't many - most CE 6 devices were netbooks.