Next Q... 'OEM unlock' greyed out

I’m in the UK, so the online chatter about Verizon doesn’t apply.
Any ideas before I send it back…?

Not quite sure if it applies to Pixels, but often a good idea to have it online, preferably with SIM card, make a couple of calls and check for software updates (but don’t actually upgrade beyond the /e/OS version to be installed).

Checking that the phone will Factory reset will check for Factory Reset Protection, if a previous owner left a Google account on the phone.

Wow - what hokus pokus black magic is this?
I put the SIM in - did the *#*#CHECKIN#*#* thing described here ‘How to Enable OEM Unlocking When Its Greyed Out?
That made no difference - so reset the phone - that made no difference (iirc) - so, took the SIM out again in preparation to send it back and factory reset the phone again - then thought to turn it back on and, with little hope, looked to the ‘OEM unlocking’ switch… And, it was active!
Go figure.
Perhaps this will be of help to someone else?
Thanks for listening.

Didn’t work for me, unfortunately. Anyone else have any ideas ?

Do it all again…
It really didn’t make any sense to me, at all!