This is mostly just a link-dump and credit where credit is due. I won’t bother repeating the whole process ad-nauseum.
The big kahuna:
XFiX’s (aka Tai1976 on this particular forum) more detailed thread about the PowerShell script bundle: https://gbatemp.net/threads/xbox-one-internal-hard-drive-upgrade-or-repair-build-any-size-drive-that-works-on-any-console.496212/
It’s worth noting that, because I do have so many drives connected to main main PC, I did have to manually edit one of the scripts in the section related to drive letters. Easy enough.
(Note that I, however, simply went back and repeated the entire original clone process and it seemed to work the second time.)
A brief note from Microsoft on the offline-system-update process: https://beta.support.xbox.com/help/hardware-network/console/system-update-solution/offline-system-update
End-result: My Xbox One S is now running a 1TB Samsung Evo 860 SSD. Granted, it’s connected via a Sata 2 interface (3Gbp/s), not Sata 3 (like you have in the Xbox One X), so I’m not really getting that much of a performance benefit, if any. BUT, it sure beats replacing with another mechanical drive, because who the heck would even buy one of those these days anyway? (Yes, for huge capacity, I get it. Not for this use-case.)
Lesson: tinkerers and geeks are awesome!