Why is my "hand tracking subsystem" not being recognized by Unity?

I hit this problem today too, only on one of my projects, with everything seemingly identical to a new empty project that works fine.  I saw the same error messages above as you.  One thing I DID notice, is that the XR\Settings\OpenXRPackageSettings, when expanded, had missing scripts causing the first set of warnings.  This was caused by me using Pico for some reason with the Quest.  Anyway, I'm digging more now into the hands part of the problem and will advise if I find the culprit. But off-hand, it is looking to me like it is very likely a corrupt settings file in /XR/Settings/, if everything else is marked off as fine.

Yes, that was totally it.  Visually, the Open XR Package Settings file looked identical, and all settings in the editor are identical when viewing the package settings file. 

Deleting it and regenerating it, everything was checked off the way it should be and still looked like it should work, but generated the error.

Replacing it from a working project, it solved it.  The file was almost twice the size (60kb instead of 32kb).  I'll attach a working copy from 202.3.21f1 should anyone need it.  Try backing up, then overwriting your file at:
\XR\Settings\OpenXRPackageSettings.  Sometimes it adds spaces to that name, some times it doesn't.  Try and reuse the same name so it picks up the old meta file.  Otherwise you'll need to reconfigure everything.

Edit: Sorry couldn't attach the file, as Oculus doesn't seem to want to let us post fixes for things.  The other way is to create a new working project and copy the file over.

Note:  If the "validation" tool tells you to regenerate the file because of duplicate settings, do not. A regenerated settings file will not work with hand tracking.

Replacing works for me. Thak you !!!!!