Hi folks, this may be amazing news for some.
Every now and again the annoying icon with an exclamation mark saying something needs to be fixed irritates me and I click on it. I've just booted my PC and clicked and the usual "you need a subscription" message didn't happen. Instead I got this:

Obviously I hit "Continue to open" and BOOM... I had read access to my archive. I tried a few more. All worked. I clicked on the three dots to the top right when you hover over the file...

You can add files.
I followed the "Learn more" to the article that tells you more. You can now manage them in Settings>General>Outlook Data Files and add them there too.
The big thing that I've found is that you can't (yet) re-arrange them into the order that you'd really like them to be in - so mine run from 2016 to 2023 and then I've added the missing 2012-2015 files and they're at the bottom (I may have to remove them all and then add them in the proper sequence in case it drives me too distraction).
Anyway, I don't know if this is rolling out slowly or if you all have access to it now, but I can certainly read my old email archives within New Outlook. Hooooooorah!