Windows Update unresponsive after win 10 upgrade

Background.
I have 3 PC's, 2 running win10 and up-to-date, and one is an old Toshiba C665 laptop that was bought new with win 7 on it. I resisted upgrade to the OS when win7 was going out of support because I thought the hardware would die first. But, no: what died 3 days ago was the browser on it that the un-tech user had to have, and a FF browser re-install required windows 10. So, as the cheaper of several options I found a windows 10 home upgrade unit on amazon. It arrived and then I found it was an OEM v1909 DVD, not the retail usb I'd expected. Not an issue: I won't ever be trying to transfer the OS from this laptop to another machine. And an in-place upgrade was the only realistic approach, since Toshiba exited the PC business years ago and the drivers the hardware uses would certainly not be available for a clean install. The existence of apps and related data for such a method certainly helped the choice.
The upgrade went without issues, and after about 90 minutes I had win 10 home running on it. The next step was getting all the updates, and the first search only yielded 1909 updates, a list a long as the screen height. Started updates going and more than 2 hours later the last one is sloowwwwlyyy installing, taking over 20 mins just to get to 75% with all the others waiting for a re-start.
At that point I elected to re-start and that may be the source of the problem explained below.
After the re-start, searching for updates (I expected a lot more to get thru including the feature releases to get up-to-date) I got a not up to date message and a one-liner saying there were several files missing. Several attempts got the same result.

I tried again this morning, without any change. A screenshot of the updates page and message is attached.

Requesting a solution
How do I get the updates page "unstuck" and running again, to get all the ones I know are out there?

That sounds easy. But can you do that: meaning upgrade to a later version of win 10 from within win 10? I have an earlier version, 21h1 in a usb which I used to upgrade an Hp laptop, but I avoided using that because I thought that the product key was also embedded in the software.

Some questions about using the iso file:
1. presumably I would have to burn a DVD from the iso file and use that or the files in it imported to the PC to upgrade, per the 2019 step-by-step guide published on this site.
2. extracting the iso file to save to a local folder - how?

In such an upgrade, would the product key used to activate 1909 be automatically transferred?

1. forget the product key !
2. rightclick on the new ISO and select "mount"
3. run setup.exe

Wait and be patient!

That link is . . complicated. I got lost just reading it. I'm familiar with using an iso file, is there a link (click on it) where I can just get the 22h2 file?

Ghot,
Thanks for a simple method. Followed it, but there's a problem; rt-clicking the desktop icon has not mount option. See attached screenshot.
Is there a fix for that missing function???

rightclick on the ISO

That's what I did and the image shows: the iso file is on the desktop, and there is no mount option in the rt-click menu

Reinstall Windows