I was eventually able to fix the issue, by updating to the most recent version, that came out in the meantime…
Being it, at the time of writing this anwser the MetaXR Plugin v.50:
https://developer.oculus.com/downloads/package/unreal-engine-5-integration/
And then, when I was looking at the output log, and traced back were he was trying to copy this .dll file from… and the files are not exactly there…
it was looking inside the Win64 folder directly…
when the files are in yet another folder called OpenXR, inside the win64 folder…
So I copied the files to the Win64 folder itself:
Tried packaging for windows… And now it works, no more ground at eye level and handtracking keeps working, as does anything else in the game.
Thanks Meta 
Hope this helps anyone having similar issues on packages.
Thanks @Astrotronic, @Cdaked, @JayLu2001 and finally @GDXRStudio for your time regarding this particular issue. You guys rock!