How can I install Media Feature Pack for N editions of Windows 11 when install exits with a "The source files could not be found" error?

Question

Having trouble with my webcam after upgrade to Windows 11 N Pro. The upgrade is on a computer which is not officially supported, since it lacks TPM.

When I start the Windows camera app I get a message that the Media Feature Pack is missing. Install via the GUI doesn't work so I tried this:

PS C:\WINDOWS\system32> dism  /online /add-capability  capabilityname:Media.MediaFeaturePack
Deployment Image Servicing and Management tool
Version: 10.0.26100.1150
Image Version: 10.0.26100.3775
[==========================100.0%==========================]
Error: 0x800f081f
The source files could not be found.
Use the "Source" option to specify the location of the files that are required to restore the feature. For more information on specifying a source location, see https://go.microsoft.com/fwlink/?LinkId=243077.
The DISM log file can be found at C:\WINDOWS\Logs\DISM\dism.log

However it exits with an error message I don't really understand what to do about.

I ran:

dism /online /cleanup-image /startcomponentcleanup

successfully, but I still can't install the Media Feature Pack.

How can I go about to troubleshoot this? What to try?

Happy for any thoughts!