Operation “Restore internet connectivity to MacBook Pro” has concluded successfully. Booting from the latest clone made on Monday was exceptionally slow. I found one (deliberately deprecated) ext SSD installation of Mojave – which will be used to run my old software that won’t work in the successor to Mojave. This one booted quickly and could get connection, so I used it to activate SuperDuper app, using the restore feature to copy the ext SSD to the Mac’s internal drive.
I wasn’t expecting the result to work well at all, just wanted to try something different since a Time Machine restoration & an attempt at reinstallation over the internet from the Recovery Drive both failed.
All's well, though. Internet is active again