No joy, I’m afraid. Either I can’t boot into recovery, or I can and after the sideload I get “no operating system found”.
This might be of interest to some. To go back to stock I would go to flash.android.com and select Android 14.0.0 and have to interact with the phone to get everything done. But if you search the for the file as Xxpsilon described it, you get a google link to the various builds. When you select the one Xxpsilon recommended you are returned to flash.android.com but the return to stock happens without you having to do anything but unplug the phone when it’s over.
Thanks for your help, folks. Cheers!