First of all thanks to all the people (particularly Jojun and Portland) who replied and also to all the posts which helped to understand in this **** situation (which should never happen: Ford does not change the clutch of your car without your permission after all)
It works !! I resumed updates and 21H2 was 0% ready to install. There was also a bunch of security updates. Done
Summing up I did the following
- With edith Group policy set 21H2 as target, reboot
- the very last day before the planned installation I deleted the content of the dir C:\Windows\SoftwareDistribution\Download Maybe this is not necessary but I did this because I was scared to resume and not having the possibility to stop it Maybe it is a good idea to snap a picture of the content of that dir before deleting the content
- reboot
- I saw that slowly the option to delay the installation increased the possible final day, up to months, which I did
- A few days later, because of my worry on security and thanks to the above suggestions I resumed and found that 21H2 was pending, and let it go
Question to Portland: did you ever change the group policy? If you did you should have now 21H2. Maybe you want rather try win11?