SO, is my “problem” now that my device (10 III) has “62.1.A.0.645 release-keys” installed, and w/ that version I get this “FAILED (remote: ‘Command did not succeed’)”
message as response from fastboot oem unlock command
(https://developer.sony.com/develop/open-devices/get-started/unlock-bootloader/ tells
“From Settings, go into Developer options and enable OEM unlocking . To do this, make sure your device is updated to the latest software .” – which may not be true after all ???)
… and I now need to to to a store to buy a windows license in order to run EMMA to install some older android version (hmm, can EMMA do that “unlock bootloader” in the list above, or is there some other command than “fastboot oem unlock” to unlock bootloader, as that is the place I a currenfly failing… so confusing…)