>On the PS5 refresh, no, an internet connection is required to activate the drive, whether or not it came in the box.
Because the disc drive and the main board are required to be paired with each other since the PS3/X360 era. People who repair PS3s (except super slims, for some reason) and PS4s need to re-pair the disc drive board with the main board (or failing both, replace both boards with one that has been already paired) every time there is drive replacement: https://www.psdevwiki.com/ps3/Remarry_Bluray_Drive (for PS3)
They've been paired for a long time as you point out; however, that's missing part of the story.
In the past, they were at least paired from the factory. If you pulled your Xbox 360 out of the box, and never connected it to the internet, it would still work.
The PS5 refresh's disc drive is not paired, even from the factory. Without an initial internet connection, it will not work, even out of the box. Also, unlike the Xbox 360, it un-pairs every time you sign out of your personal account.
Because the disc drive and the main board are required to be paired with each other since the PS3/X360 era. People who repair PS3s (except super slims, for some reason) and PS4s need to re-pair the disc drive board with the main board (or failing both, replace both boards with one that has been already paired) every time there is drive replacement: https://www.psdevwiki.com/ps3/Remarry_Bluray_Drive (for PS3)